Patent Publication Number: US-6705304-B1

Title: Crossbow cocking mechanism

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/374,570, filed Apr. 23, 2002. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to crossbows. 
     More particularly, the present invention relates mechanisms for drawing the bow string of a crossbow from a released position to a drawn position. 
     BACKGROUND OF THE INVENTION 
     Crossbows are well known projectile devices that have been around for centuries. During most of that time, the basic structure of the crossbow has remained relatively unchanged, with modifications to the trigger mechanism, changes in the materials used in its construction and many innovations in devices and mechanisms for drawing the bowstring into the cocked position. A large amount of time an effort has been expended on developing a simple and easily used cocking mechanism over the years. However, each has been less than satisfactory. The simplest form of cocking is performed manually. The bow string is grasped by hand or hands, and drawn to the cocked position. This method is simple and quick, but becomes more difficult as the draw weight of the bow increases. Claws, hooks, etc. with handles, are often utilized to provide a better grip on the bow string. However, strength is still needed to draw the bow string. Over the years external mechanical aids have also been developed. These, however, are typically bulky, difficult to use and inconvenient to carry with the crossbow. 
     More successful are devices that are attached to or carried by the crossbow. These devices include cranks and levers for drawing the bow string into the cocked position. Cranks most simply pull a line connected to the bow string onto a spindle. Levers employ one or more lever elements to pull the bow string back. Each is effective, but can be cumbersome and awkward to employ. 
     It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art. 
     Accordingly, it is an object of the present invention to provide a new and improved crossbow cocking mechanism. 
     Another object of the invention is to provide a crossbow cocking mechanism which is inexpensive and easy to use. 
     And another object of the invention is to provide a crossbow cocking mechanism which provides a mechanical advantage to overcome the draw weight of the crossbow. 
     SUMMARY OF THE INVENTION 
     Briefly, to achieve the desired objects of the instant invention in accordance with a preferred embodiment thereof, provided is a crossbow including a stock having a forward end an a rearward end, a bow member mounted on the stock proximate the forward end, and having a bow string movable between a released position and a drawn position. A trigger mechanism is carried by the stock, and includes a trigger coupled to a latch. The latch for engages and holds the bow string in the drawn position and selectively releases the bow string into the released position when disengaged. A cocking mechanism is carried by the stock and includes a string engaging member moveable between a ready position and a cocked position. The string engaging member includes a hook portion engaging the bow string in the released position and drawing the bow string to the drawn position when moved to the cocked position. A slide is slidably mounted to an underside of the stock and movable forwardly toward the forward end and rearwardly toward the rearward end. A first guide is mounted to the stock proximate the forward end and a second guide is mounted to the stock proximate the rearward end. A line has an end coupled to the slide and an opposing end coupled to the string engaging member. The line extends forwardly from the grip around the first guide, extends rearwardly from the first guide around the second guide and extends forwardly to couple to the string engaging member. 
     In a further embodiment of the invention, a second line with guides is attached between the slide and the string engaging member. In yet another embodiment, the end of the line is coupled to the string engaging member with a cocking cog in a block and tackle arrangement. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and further and more specific objects and advantages of the instant invention will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment thereof taken in conjunction with the drawings, in which: 
     FIG. 1 is a perspective view illustrating a crossbow according to the present invention, illustrated in a cocked configuration; 
     FIG. 2 is a perspective view of the crossbow of FIG. 1, illustrated in a released configuration; 
     FIG. 3 is a side view of the crossbow of FIG. 1, illustrated in the released configuration; 
     FIG. 4 is a side view of the crossbow of FIG. 1, illustrated in the cocked configuration; 
     FIG. 5 is a reverse side view of the crossbow of FIG. 3; and 
     FIG. 6 is an enlarged partial perspective view of the crossbow with portion broken away. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to the drawings in which like reference characters indicate corresponding elements throughout the several views, attention is first directed to FIG. 1 which illustrates a crossbow generally designated  10 . Crossbow  10  is substantially of any conventional construction, and includes a stock  12  having a rearward end  13  from which a butt portion  14  extends, and a forward end  17 . Stock  12  includes a slide  18  to mount a bolt, and carries a bow  20  with bow string  22  proximate forward end  17 . Bow string  22  is movable between a released position (FIG.  2 ), and a drawn position (FIG. 1) wherein bow string  22  is pulled toward rearward end  13 . A trigger mechanism is carried by stock  12  and includes a trigger  24  mounted proximate rearward end  13  and a latch  25 . Latch  25  engages and retains bow string  22  in the drawn position and selectively releases bow string  22  into the released position when disengaged from bow string  22 . The trigger mechanism, including links between trigger  24  and latch  25 , is not described in further detail, as substantially any trigger mechanism can be employed, and these mechanisms are well known in the art. 
     A cocking mechanism, generally designated  30  is carried by stock  12 , and operates to move bow string  22  from the released position to the drawn position, where bow string  22  is engaged by latch  25  and held until trigger  24  is actuated. Cocking mechanism  30  includes a reciprocating slide  32  slidably mounted to the underside of stock  12  by a track  33 . Forward and rearward reciprocating movement of slide  32  can be facilitated by the use of bearings or the like, and it will be understood that track  33  can be rails, grooves, rods, etc. 
     Referring to one side of crossbow  10 , a line  34  has an end  35  coupled to slide  32  and an end  37  coupled to stock  12  at an anchor  38  proximate rearward end  13 , rearward of latch  25 . Line  34  is a flexible elongated member, such as a string, rope cable, strap, etc. A guide  40  is mounted to stock  12  proximate forward end  17  and a guide  42  is mounted to stock  12  proximate rearward end  13  and below anchor  38 . Line  34  extends forwardly from slide  32  and passed around guide  40  to extend rearwardly and pass around guide  42 . A segment of line  34  between guide  42  and anchor  38  is increased when slide  32  is moved forwardly, towards forward end  17 , and decreased when slide  32  is moved rearwardly, toward rearward end  13  for reasons which will be described presently. It will be understood by those skilled in the art that guides  40  and  42  are intended to position line  34  and allow line  34  to easily pass therearound. To this end, guides  40  and  42  are preferably wheels to reduce drag or friction on line  34 . However, it will be understood that other guides may be employed, such as posts, rollers and the like. 
     Additionally, while only one side of crossbow  12  has been described in detail, with reference to FIG. 5, the same arrangement is provided for the other side of crossbow  10 . A line  34 ′ has an end  35 ′ coupled to slide  32  and an end  37 ′ coupled to stock  12  at an anchor  38 ′ proximate rearward end  13 , rearward of latch  25 . Line  34 ′ extends around guides  40 ′ and  42 ′. Only one side is described in detail, as they are substantially identical. 
     Referring back to FIGS. 1-4, a cocking cog  44  is reciprocally mounted within a channel  45  formed in stock  12  intermediate latch  25  and anchor  38 . With additional reference to FIG. 6, cocking cog includes pulleys  47  and  48  coupled by an axle  49 . The segment of line  34  between guide  42  and anchor  38  passes around pulley  47  while the like portion of line  34 ′ passes around pulley  48 . A string engagement member  50  is slidably carried by stock  12  and movable between a ready position and a cocked position. String member  50  includes a pair of rods  52  each terminating in a hook portion  53  at a forward end, and having the rearward end coupled to axle  49  of cocking cog  44 . Typically, hook portion  53  is bifurcated so as to engage bow string  22  on either side of a portion to be engaged by latch  25 . Therefore, two rods can be provided each terminating in a hook and coupled to axle  49 , one rod can be provided terminating in a double hook, or conceivably, a single hook can be provided, although this is less efficient. 
     Thus, as slide  32  is moved rearwardly, cocking cog  44  and string engagement member  50  are also moved rearwardly to a cocked position, drawing bow string  22  into the drawn position. In the drawn position, bow string  22  is engaged and held by latch  25 . When slide  32  is released, a biasing mechanism  60  pulls cocking cog  44  string engagement member  50  and slide  32  forwardly into a ready position again. In the ready position, string engagement member  50  is ready to draw bow string  22  back into the drawn position when released from latch  25 . Biasing mechanism  60  includes tension springs  62  and  63  mounted on apposing sides of crossbow  10  with one end anchored to stock  12  and the other end coupled to cocking cog  44 . 
     A mechanical advantage is provided by the block and tackle arrangement of cocking cog  44 . In the preferred embodiment, as slide  32  is moved a certain distance, cocking cog  44  moves half that distance. This reduces the effort needed to overcome the draw weight of bow  20 . Thus, a bow with greater draw weight can be used with less effort. As illustrated, a simple block and tackle has been created by guide  42  and  42 ′ and cocking cog  44 . In this instance, the ends  37  and  37 ′ of lines  34  and  34 ′ are coupled to string engaging member  50  by a block and tackle. A more complex one can be employed to increase the advantage. Those skilled in the art will understand that the advantage created by the block and tackle can be increased or eliminated as desired, according to the arrangement of the pulleys, positioning of anchor  38 , etc. Additionally, the block and tackle arrangement can be removed, with ends  37  and  37 ′ of lines  34  and  34 ′ coupled directly to string engagement member  50 , eliminating anchor  38  and cocking cog  44 . In this example, a pump action cocking mechanism is provided with no mechanical advantage. 
     Various changes and modifications to the embodiments herein chosen for purposes of illustration will readily occur to those skilled in the art. For example, while the lines and guides are illustrated on the outside of the stock, it will be understood that a stock can be created containing channels and spaces for a single set of guides and one line passing through the middle thereof. To the extent that such modifications and variations do not depart from the spirit of the invention, they are intended to be included within the scope thereof which is assessed only by a fair interpretation of the following claims.