Abstract:
An arm is attached to a mounting body at a first attachment. The arm is configured and arranged to move between an open position and a closed position. The arm has a first surface that in combination with a second surface on the mounting body forms a cavity for holding a fixed blade knife in a locked position when the arm is attached to the mounting body at a second attachment.

Description:
TECHNICAL FIELD 
     The present invention relates generally to the field of weapons, and more particularly to an adaptor for use with a rail system on a firearm and a method of using such an adaptor. 
     BACKGROUND ART 
     Current military bayonets designed with the M4 Carbine/M16 platform are limited as to the weapons that can be mounted to the outside of the platform. Mounts for these bayonets usually consist of a lug that is fixed to the barrel of the firearm. The lug protrudes down from barrel where it combines with the muzzle ring of the bayonet. The muzzle ring slides over the muzzle and allows the lug to fix the bayonet in place. This design limits the mounting of current bayonets to weapons that have a sufficient length of exposed barrel to accommodate the length of the handle on the bayonet and that have the barrel circumference to accommodate the muzzle ring. What is needed is an adaptor that overcomes these drawbacks. 
     BRIEF SUMMARY OF THE INVENTION 
     With parenthetical reference to the corresponding parts, portions or surfaces of the disclosed embodiment, merely for the purposes of illustration and not by way of limitation, the present invention provides an adaptor ( 10 ) for receiving a fixed blade knife ( 160 ). The adaptor ( 10 ) includes a mounting body ( 13 ) configured to operatively attach to a rail system ( 157 ) of a firearm ( 206 ). An arm ( 19 ) is attached to the mounting body ( 13 ) at a first attachment ( 22 ). The arm ( 19 ) is configured and arranged to move between an open position and a closed position. The arm ( 19 ) has a first surface ( 43 ) that in combination with a second surface ( 58 ) on the mounting body ( 13 ) forms a cavity ( 59 ) for holding the fixed blade knife ( 160 ) in a locked position when the arm ( 19 ) is attached to the mounting body ( 13 ) at a second attachment ( 41 ). 
     The adaptor ( 10 ) may further comprise the arm ( 19 ) having a first end ( 28 ) that is pivotally attached to the mounting body ( 13 ) at the first attachment ( 22 ). 
     The adaptor ( 10 ) may further comprise the first surface ( 43 ) having a recessed portion ( 46 ) for receiving a butt cap ( 175 ) on the knife ( 160 ). 
     In another aspect, one of the arm ( 19 ) and the mounting body ( 13 ) include at least one locking tab ( 37 ). 
     In another aspect, one of the arm ( 19 ) and the mounting body ( 13 ) have an opening ( 40 ) for receiving the locking tab ( 37 ) therethrough. 
     The adaptor ( 10 ) may further comprise the first surface ( 43 ) and the second surface ( 58 ) having at least one groove ( 49 ) defined therein for receiving at least one O-ring ( 178 ) disposed around the handle ( 166 ) of the knife ( 160 ). 
     The adaptor ( 10 ) may further comprise the mounting body ( 13 ) receiving a cooperating member ( 88 ) such that a portion of the mounting body ( 13 ) and a corresponding portion of the cooperating member ( 88 ) form a channel ( 106 ) when the cooperating member ( 88 ) is attached to the mounting body ( 13 ). 
     In another aspect, the mounting body ( 13 ) has an edge disposed adjacent to a recessed portion forming a shoulder ( 61 ). 
     In another aspect, the arm ( 19 ) has an edge configured to engage with the shoulder ( 61 ) when the arm ( 19 ) is attached to the mounting body ( 13 ). 
     In another aspect, the arm ( 19 ) includes longitudinally spaced protrusions ( 130 ) configured to grip the handle ( 166 ) of a knife ( 160 ). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevational view of the adaptor of the present invention in the open position. 
         FIG. 2  is a side elevational view of the adaptor shown in  FIG. 1  in a closed position. 
         FIG. 3  is a cross-sectional view taken along lines  3 - 3  of  FIG. 2 . 
         FIG. 4  is a cross-sectional view taken along lines  4 - 4  of  FIG. 2 . 
         FIG. 5  is a detailed cross-sectional view of a portion of  FIG. 4 . 
         FIG. 6  is a front perspective view of the adaptor in the open position. 
         FIG. 7  is a front elevational view of the adaptor of  FIG. 6  attached to a rail system. 
         FIG. 8  is an exploded view of the adaptor of the present invention. 
         FIG. 9  is a left side elevational view of the adaptor of the present invention holding a fixed blade knife. 
         FIG. 10  is a cross-sectional view taken along lines  10 - 10  of  FIG. 9 . 
         FIG. 11  is a cross-sectional view taken along lines  11 - 11  of  FIG. 10 . 
         FIG. 12  is an elevational view of the adaptor of the present invention shown in an open position with a fixed blade knife disposed therein. 
         FIG. 13  is a side elevational view of a firearm with an adaptor of the present invention mounted on a rail system and shown in the open position with a fixed blade knife disposed therein. 
         FIG. 14  is a side elevational view of a firearm with an adaptor of the present invention mounted on a rail system and shown in the closed position. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     At the outset, it should be clearly understood that like reference numerals are intended to identify the same structural elements, portions or surfaces consistently throughout the several drawing figures, as such elements, portions or surfaces may be further described or explained by the entire written specification, of which this detailed description is an integral part. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, debris, etc.) together with the specification, and are to be considered a portion of the entire written description of this invention. As used in the following description, the terms “horizontal”, “vertical”, “left”, “right”, “up” and “down”, as well as adjectival and adverbial derivatives thereof, (e.g., “horizontally”, “rightwardly”, “upwardly”, etc.), simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader. Similarly, the terms “inwardly” and “outwardly” generally refer to the orientation of a surface relative to its axis of elongation, or of rotation, as appropriate. 
     Referring now to the drawings, and as shown in  FIGS. 1-2 , an adaptor  10  may be provided with a mounting body  13 . Mounting body  13  may be attached to a rail mounting system  157  ( FIG. 8 ) by a plurality of fasteners  91 . An arm  19  may be attached to the mounting body  13  at a first attachment  22 . The arm  19  may be pivotally attached by a pivot pin  25  as will be evident to those of ordinary skill in the art based on this disclosure. The arm  19  may have a proximal end  28  disposed near the pivot pin  25  and a distal end  31  disposed opposite from the proximal end  28 . The distal end  31  may be provided with a projecting portion  34 . The projecting portion  34  may be provided with a locking tab  37 . The locking tab  37  and projecting portion  34  may be formed from a resilient thermoplastic material such that the locking tab  37  is capable of flexing inward when the arm  19  is rotated up (counterclockwise in  FIG. 1 ) into position in the mounting body  13 . The locking tab  37  flexes inward until it aligns with an opening  40  formed in the mounting body  13 . When the locking tab  37  aligns with the opening  40  it deflects outward into the opening  40  to form a second attachment  41 . When the tab  37  is deflected outward inside the opening  40  it prevents the arm  19  from moving relative to the mounting body  13  and locks the arm  19  into a fixed position shown in  FIG. 2 . 
     Turning to  FIG. 3 , the arm  19  has an inner surface  43  that may be curved. The inner surface  43  extends from the distal end  31  toward the opposite end. A recessed portion  46  is disposed adjacent to the inner surface  43 . The recessed portion  46  may be sized to receive the butt cap  175  on a knife  160  as will described in detail herein. The surface  43  may be provided with a plurality of grooves  49  defined therein. The grooves  49  may be spaced apart in the longitudinal direction. 
     Referring to  FIGS. 4-5 , arm  19  may include a locking tab  37  on opposite sides. The locking tab  37  has a shoulder  52  and an angled portion  55 . The locking tab  37  is mounted on the projecting portion  34 . The projecting portion  34  is resilient and capable of flexing inward such that the angled portion  55  can slide past bar  73  on the mounting body  13  until the angled portion  55  reaches an opening  40  (best shown in  FIG. 8 ) formed in the mounting body  13 . When the locking tab  37  is disposed in alignment with the opening  40 , the projecting portion  34  springs outward and the shoulder  52  engages with bar  73  (as best shown in  FIG. 5 ) to lock the arm  19  into position relative to the mounting body  13 . Returning to  FIG. 4 , the inner surface  43  of the arm  19  and the inner surface  58  of the mounting body  13  combine to form an elongate cavity  59  that may have an oval cross section. The cavity  59  is sized to fit the knife  160  as described in greater detail herein. 
     In  FIG. 5 , the inner surface  58  of the mounting body  13  extends to a shoulder  61  that is formed at an edge where the mounting body  13  and arm  19  are disposed in close proximity when the arm  19  is engaged with the mounting body  13 . The shoulder  61  is formed between a projecting portion  64  and the inner surface  58 . The arm  19  may be formed with a corresponding projecting portion  67  that abuts with the shoulder  61  when the arm  19  is engaged with the mounting body  13 . The arm  19  is also provided with a shoulder  70  that receives the projecting portion  64 . The locking tab  37  engages with a bar  73  disposed on the mounting body  13 . The bar  73  borders the opening  40  that receives the locking tab  37 . 
     Returning to  FIG. 4 , the mounting body  13  may be formed at the top with a projecting member  76  having surfaces forming a portion of a channel  106  for receiving a rail on a rail mounting system for a firearm as will be described in greater detail herein. Surface  79  borders an opening  82  and is disposed in facing relation with surface  85  on a cooperating member  88  that may be attached to the mounting body  13  by a fastener  91  (best shown in  FIGS. 6-8 ) as described in detail herein. Additional surfaces  94  and  97  on the mounting body  13  cooperate with surfaces  100  and  103  on the cooperating member  88  and top surface  105  to form the channel  106  for receiving the rail of a rail mounting system  157 . Mounting body  13  includes angled outer surfaces  95 ,  96 ; and cooperating member  88  may include angled outer surfaces  107 ,  108 . 
     Referring to  FIGS. 6-8 , and initially to  FIG. 8  the fastener  91  may include a thumbwheel head  109  mounted or integrally formed at one end. The opposite end of the fastener  91  may be secured by a nut  112 . The mounting body  13  has a plurality of openings  115  for receiving the fastener  91 . The cooperating member  88  has a plurality of openings  118  for receiving the fastener  91 . The mounting body  13  may also include an opening  121  for receiving the pivot pin  25 . The arm  19  has an opening  127  that aligns with the opening  121  and receives the pivot pin  25  to form the first attachment  22  ( FIG. 1 ). The distal end  31  of the arm  19  pivots about the pivot axis  128  (normal to the page in  FIG. 2 ). The arm  19  may be designed to rotate counterclockwise about the pivot axis  128  from the open position shown in  FIG. 1  to the closed position shown in  FIG. 2 . When the arm  19  is rotated counterclockwise about the pivot axis  128 , the angled portion  55  of the locking tab  37  slides across the bar  73 . As the arm  19  rotates, the bar  73  deflects the projecting portion  34  inward to allow the locking tab  37  to slide across the bar  73 . When the angled portion  55  clears the bar  73 , the locking tab  37  springs outward into the opening  40  according to the elastic properties of the resilient material forming the projecting portion  34 . Once the locking tab  37  springs outward the shoulder  52  of the locking tab  37  engages with the bar  73  to prevent any additional movement of the arm  19  relative to the mounting body  13 . To release the arm  19  from the mounting body  13 , the locking tabs  37  are pushed inward until the shoulder  52  of the locking tab  37  clears the bar  73 . It will be evident to those of ordinary skill in the art based on this disclosure, that the arm  19  can be directly attached to the mounting body  13  without a pivotal attachment. Accordingly, the arm  19  may also be attached to the mounting body  13  through translational motion. In one example, the mounting body  13  could be provided with bars  73  and openings  40  in the front and rear of the mounting body  13 . The arm  19  could be provided with projecting portions  34  having locking tabs  37  at both the front and rear and the arm  19  could be attached to the mounting body  13  by means of translational motion. Other mechanisms for mounting the arm  19  to the mounting body  13  will also be evident to those of ordinary skill in the art based on this disclosure. 
     Turning to  FIG. 6 , the arm  19  is shown in the open position. The plurality of grooves  49  may be formed along the length of the inner surface  43 . A plurality of projecting portions  130  may extend outward from the inner surface  43 . The projections  130  are best shown in  FIG. 7 . The grooves  49  may be provided to receive O-rings  178  ( FIG. 11 ) attached to the handle  166  of the knife  160  such as a KA-BAR brand fixed blade knife. As shown in  FIG. 7 , the projections  130  may extend into the channel  59  and make contact with the handle of the knife to prevent it from sliding or moving inside the channel  59 . Returning to  FIG. 6 , at the back of the arm  19  the recessed portion  46  may be designed to receive the butt cap  175  ( FIG. 10 ) of the knife  160 . The shoulder  70  on the arm  19  extends along the length of the arm  19 . The inner surface  58  of the mounting body  13  combines with the inner surface  43  of the arm  19  to form the channel  59 . 
     Returning to  FIG. 8 , the mechanism for locking the arm  19  into position relative to the mounting body  13  is shown in greater detail. The bar  73  is disposed in spaced apart relation from the side of the mounting body  13  and is supported at opposite ends by supports  133  extending from a side wall  139  of the mounting body  13 . The projecting portion  34  may be cantilevered such that a lower portion  142  may attach to a portion  145  of the base  148  of the arm  19 . The projecting portion  34  extends approximately parallel to the side wall  151  of the arm  19 . The cantilever arrangement of the projecting portion  34  provides the projecting portion  34  with the ability to flex toward and away from the arm  19  according to the material properties. The arm  19  may be constructed from a molded plastic with a thickness where the projection portion  34  attaches to the arm  19  that is thick enough to be flexible yet resilient such that after bending the projecting portion  34  returns to its original shape. The material is also sufficiently thick to avoid breaking. At the top of the figure, the cooperating member  88  is an elongate generally wedge shaped member that is received on a shelf  154  that is formed in the top of the mounting body  13 . As best shown in  FIG. 7 , the cooperating member  88  fits onto the shelf and nests into an opening formed in the top of the mounting body  13 . When the cooperating member  88  is attached to the mounting body  13  by means of the fastener  91 , the system can be supported from a rail mounting system  157 . The rail mounting system  157  may comprise a picatinny system or any other system for mounting attachments on a rail disposed on a firearm. 
     Turning to  FIGS. 9-11 , a fixed blade knife  160  is shown in position in the adapter  10 . The knife  160  has a blade  163 , a handle  166  ( FIGS. 10-11 ), and a bolster  169 . It will be evident to those of ordinary skill in the art based on this disclosure that a locking blade knife may also be suitable for use with the adaptor  10  of the present invention. The knife  160  may be a KA-BAR brand fixed blade knife with a plurality of grooves  172  spaced apart along the length of the handle  166 . A butt cap  175  may be disposed at the end of the handle  166 . The grooves  172  may be provided with O-rings  178  ( FIG. 11 ) that cooperate with the grooves  49  along the length of the adapter  10  to provide a secure fit and to help prevent the knife  160  from sliding or rotating inside channel  59 . The butt cap  175  may be received in the recessed portion  46 . The recessed portion  46  holds the butt cap  175  and prevents axial movement of the knife  160  along the longitudinal axis inside cavity  59 . 
     In  FIG. 11 , the pivot point  128  is shown. Also the fasteners  91  are shown at the top of the figure. 
     Turning to  FIG. 12 , the arm  19  is shown in the open position where the locking tabs  37  have been released from engagement with the bars  73  and the arm  19  has been rotated clockwise in the direction of arrow  180 . The arm  19  may engage with the majority of the handle  166  but leave clearance for the bolster  169  which is disposed outside of the adapter  10 . From the position shown, the arm  19  is rotated counterclockwise in the direction of arrow  183  to secure the knife  160  in position. The angled portion  55  of locking tab  37  engages with the bar  73  and the projecting portion  34  deflects inward until the angled portion  55  clears the bar  73 . At that point the material properties of the projecting portion  34  cause it to spring into position with the shoulder  52  engaged with the bar  73  as best shown in  FIG. 5 . In this position, the adapter  10  is locked into position with the arm  19  and the mounting body  13  forming the cavity  59  that receives the knife  160 . The adapter  10  is mounted on rail system  157  by means of the thumbwheel heads  109  on fasteners  91 . The rail is elongate and has a generally T-shaped cross section that mates with groove  106  to hold adapter  10  securely in position on the rail. The rail has gaps along its length to provide clearance for receiving fasteners  91  as will be described in greater detail herein. 
     Turning to  FIGS. 13-14 , the rail mounting system  157  is shown along the top and bottom surfaces  200 ,  203  of a large caliber firearm  206  such as an M4 Carbine/M16 platform. The rail mounting system  157  may comprise a series of ridges with a T-shaped cross-section (best shown in  FIG. 7 ). The ridges are interspersed with flat spacing slots  209 . The top of the mounting body  13  slides over the rail  157  as best shown in  FIG. 7 . The mounting body  13  is locked into position on the rail  157  by sliding fastener  91  through the openings in the mounting body  13  and the cooperating member  88  and through the slot  209 . The fastener  91  is locked in place by means of the thumbwheel  109  and the nut  112 . The rail systems were originally intended for mounting scopes on top of the receivers of large caliber rifles but the uses have expanded to include accessories such as tactical lights, laser aiming modules, night vision devices, reflex sights, foregrips, bipods, and bayonets. In  FIG. 13 , a pair of accessories  215 ,  218  are mounted to the rail system  157  on the top of the firearm. The adapter  10  is mounted on the opposite side of the barrel. The adapter  10  is shown in the open position with the knife  160  supported on the inner surface  43  of the arm  19 . The arm  19  may pivot toward the mounting body  13  as described above until the locking tab  37  is seated in the opening  40  and the shoulder  52  is engaged with the bar  73  as shown in  FIG. 14 . 
     The present invention contemplates that many changes and modifications may be made. Therefore, while the presently-preferred form of the adaptor has been shown and described, and several modifications and alternatives discussed, persons skilled in this art will readily appreciate that various additional changes and modifications may be made without departing from the spirit of the invention, as defined and differentiated by the following claims.