Abstract:
The pneumatically driven projectile weapon combines the tensioned line of a conventional crossbow or archery bow with mechanical and pneumatic compression, thus increasing the power and accuracy of the weapon. A spring-biased cylinder is mounted within a hollow weapon stock, similar to a conventional rifle or shotgun stock, and is interconnected via an internal pulley system to the tensioned line. Firing tension in the line to launch a projectile, such as an arrow or the like, is created by compression of the spring-biased pneumatic cylinder.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to weapons, and particularly to a pneumatically driven projectile weapon (a cross between a crossbow and an air gun) combining a tensioned line with a spring-biased pneumatic cylinder to launch a projectile (an arrow or dart). 
         [0003]    2. Description of the Related Art 
         [0004]    A crossbow is a weapon having a bow mounted on a stock that shoots projectiles, similar to conventional arrows. A conventional crossbow is relatively bulky, due to the necessity of the bow portion, thus making it inefficient for carrying during hunting or other recreational or sport activities. Additionally, the crossbow, as with the conventional bow, is limited in firing power by the maximum tension of which the bow is capable of achieving. It would be desirable to combine the capabilities of a crossbow with the portability and convenience of a conventional hunting weapon, such as a rifle or shotgun, and to further increase firing power without the structural limitations of a conventional bow. 
         [0005]    Thus, a pneumatically driven projectile weapon solving the aforementioned problems is desired. 
       SUMMARY OF THE INVENTION 
       [0006]    The pneumatically driven projectile weapon includes a hollow weapon stock, similar to a conventional rifle or shotgun stock. A longitudinal track adapted for slidably receiving an arrow is defined in an upper end thereof. A retainer is slidably disposed within the longitudinal track. The retainer is adapted for releasably engaging a rear end of the arrow, similar to a conventional crossbow. 
         [0007]    A spring-biased cylinder having opposed first and second ends is mounted within the hollow weapon stock and extends longitudinally therein. The spring-biased cylinder is preferably a pneumatic cylinder, thus allowing for both pneumatic and mechanical compression and expansion, although it should be understood that the cylinder may be solely spring-biased. A first pair of pulleys is mounted within the hollow weapon stock adjacent the first end of the spring-biased cylinder. The pulleys are spaced apart and are positioned adjacent laterally opposed sides, respectively, of the first end of the spring-biased cylinder. 
         [0008]    A second pair of pulleys is mounted on the second end of the spring-biased cylinder. The pulleys of the second pair are similarly spaced apart and positioned on laterally opposed sides, respectively, of the second end of the spring-biased cylinder. A cable has opposed ends fixed within the hollow weapon stock adjacent and beneath the first pair of pulleys. First portions of the cable adjacent the ends thereof are partially wound about the second pair of pulleys, and second portions of the cable are partially wound about the first pair of pulleys. A central portion of the cable is secured to the sliding retainer. 
         [0009]    The sliding retainer is releasably held in the rear end of the longitudinal track by a trigger-actuated release, as in a conventional crossbow, When the retainer is held in the rear end of the longitudinal track by the release, the cable is tensioned to compress the spring-biased cylinder. When the retainer is released, longitudinal expansion of the spring-biased cylinder drives the retainer to slide within the longitudinal track toward a front end thereof, imparting forward momentum to the arrow. 
         [0010]    These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a diagrammatic side view of a pneumatically driven projectile weapon according to the present invention, showing the cylinder extended. 
           [0012]      FIG. 2  is a diagrammatic side view of a pneumatically driven projectile weapon according to the present invention, showing the cylinder compressed. 
           [0013]      FIG. 3  is a diagrammatic perspective view of a cable and pulley mechanism of the pneumatically driven projectile weapon. 
           [0014]      FIG. 4  is a diagrammatic top view of an alternative embodiment of a pneumatically driven projectile weapon according to the present invention. 
       
    
    
       [0015]    Similar reference characters denote corresponding features consistently throughout the attached drawings. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    As best shown in  FIGS. 1 and 2 , the pneumatically driven projectile weapon  10  includes a hollow weapon stock  12 , similar to a conventional rifle or shotgun stock. A longitudinal track  14  adapted for slidably receiving an arrow A (shown in  FIG. 2 ) is defined in an upper surface of the stock  12 . A retainer  26  is slidably disposed within the longitudinal track  14 . The retainer  26  is adapted for releasably engaging a rear end of the arrow A, similar to a conventional crossbow. It should be understood that the weapon stock  12 , along with the attached scope  42 , are shown for exemplary purposes only, and that any desired style or size of weapon stock (or any desired type of attachment) may be utilized. 
         [0017]    A spring-biased cylinder  16  having opposed first and second ends  18 ,  20  is mounted within the hollow weapon stock  12  and extends longitudinally therein. The spring-biased cylinder  16  is preferably a pneumatic cylinder, thus allowing for both pneumatic and mechanical compression and expansion, although it should be understood that the cylinder may be solely spring-biased. The cylinder  16  comprises two tubes, each of the tubes having a closed end, one of the tubes being slidable within the other. The first end  18  of the spring-biased cylinder  16  is fixed within the hollow weapon stock  12 , and the second end  20  is free to move in axially during expansion and compression of cylinder  16 , sliding within the first end  18 . 
         [0018]    A first pair of pulleys  22  is mounted within the hollow weapon stock  12  adjacent the first end  18  of the spring-biased cylinder  16 . The pulleys  22  are spaced apart and are positioned adjacent laterally opposed sides, respectively, of the first end of the spring-biased cylinder  16 . A second pair of pulleys  24  is mounted on the second end  20  of the spring-biased cylinder  16 . The pulleys  24  of the second pair are similarly spaced apart and mounted on laterally opposed sides, respectively, of the second end  20  of the spring-biased cylinder  16 . 
         [0019]    A cable  28  has opposed ends  30  fixed within the hollow weapon stock  12  adjacent and beneath the first pair of pulleys  22 . The configuration of the cable  28  with respect to the pulleys is shown diagrammatically in  FIG. 3 . First portions  32  of the cable  28  adjacent the ends  30  are partially wound about the second pair of pulleys  24 , and second portions  34  of the cable  28  are partially wound about the first pair of pulleys  22 . A central portion  36  of the cable  28  is secured to the sliding retainer  26 . 
         [0020]    The sliding retainer  26  is releasably held in the rear end of the longitudinal track  14  by a trigger-actuated release  38  (actuated by trigger  40 ), as in a conventional crossbow. Such firing mechanisms are known in the field of crossbows. Examples of such firing mechanisms are shown in U.S. Pat. Nos. 3,561,419; 5,749,348; and 6,286,496, each of which is hereby incorporated by reference in its entirety. When the retainer  26  is held in the rear end of the longitudinal track  14  by the release  38 , the cable  28  is drawn over the pulley pairs  22 ,  24 , compressing the compression spring  50  within the cylinder  16  and placing the cable  28  under tension. When the retainer  26  is released, the compression spring  50  is released so that longitudinal expansion of the spring-biased cylinder  16  drives the retainer  26  to slide within the longitudinal track  14  toward the front end thereof, imparting forward momentum to the arrow A. 
         [0021]    It should be understood that the weapon  10  may be used to fire any suitable type of projectile, rather than only the exemplary arrow A shown in  FIG. 2 . For example, weapon  10  may be adapted to fire bolts or quarrels, as are commonly shot from conventional crossbows. 
         [0022]    Further, as shown in  FIGS. 1 and 2 , an adjustable sliding holder  44  may be mounted within the first end of the spring-biased cylinder. A first end of the compression spring  50  engages the adjustable sliding holder  44 . The second end of the compression spring  50  is fixed to the slidable second end  20  of the spring-biased cylinder  16 . The adjustable sliding holder  44  is longitudinally adjustable to selectively adjust the length to which the compression spring  50  expands, thus allowing for fine control over the firing power of the weapon  10 . The adjustable sliding holder  44  may be adjusted by a threaded member  46  extending through a front end of the hollow weapon stock and through the first end  18  of the internally spring-biased cylinder  16 , as shown, to contact the adjustable sliding holder  44 . 
         [0023]    In the alternative embodiment of  FIG. 4 , the weapon  100  is configured similar to weapon  10 , including a hollow stock  112 , a first pair of pulleys  122 , a second pair of pulleys  124 , an spring-biased cylinder  116 , a cable  128 , and a sliding retainer  126 , each of which functions similar to that described above with regard to the weapon  10 . However, in the embodiment of  FIG. 4 , a bow  150 , similar to that of a conventional crossbow, has been added. The bow  150  has a pair of laterally opposed ends and a central portion secured to a front end of the hollow weapon stock  112 . A third pair of pulleys  152  is rotatably mounted to the opposed ends of the bow  150  so that the central portion of the cable  128  is partially wound about the third pair of pulleys  152  external to the hollow weapon stock  112 , similar to a conventional crossbow. In this embodiment, the pulleys  124  of the first pair rotate about a lateral axis, as in the previous embodiment. However, the second and third pairs of pulleys  122 ,  152  rotate about vertical axes orthogonal to the lateral axis and the longitudinal axis of the stock  112 . 
         [0024]    It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.