Abstract:
The present invention relates to folding knives and implements, and more specifically to a locking mechanism used to prevent the inadvertent closing of the knife blade as well as overextension of the knife blade during use.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to hand held folding knives, and more specifically folding knives which have a locking mechanism for engaging the blade to prevent the blade from inadvertently closing.  
         BACKGROUND OF THE INVENTION  
         [0002]    Pocket knives are commonly used by sportsmen, craftsmen and others who desire a compact, portable blade which can be safely folded and transported in a pocket or attached to a belt. Unfortunately, many of the folding blades commonly associated with these types of pocket knives do not have locking mechanisms to prevent the blades from inadvertently closing. Thus, the folding knife can be potentially dangerous to use if the sharpened blade inadvertently closes.  
           [0003]    More recently, locking devices have been incorporated into folding knives to prevent the inadvertent closing of the knife blade. One type of locking mechanism known in the art is a “liner lock” which utilizes a leaf spring positioned within the cavity of the knife handle and which engages the heel end of the knife blade. The blade is typically released by the user by applying finger pressure to the leaf spring, thus releasing the leaf spring from the knife blade.  
           [0004]    Another commonly used folding knife locking mechanism is a “back lock”, which utilizes a locking bar positioned along an upper edge of the knife handle. When finger pressure is applied to a rear portion of the locking bar, a tang interconnected to a forward portion of the locking bar is withdrawn from a cut-out “anvil” located in the heel end of the blade. When the tang is released from the anvil, the knife blade is allowed to rotate between a first extended position of use and a second closed position wherein at least a portion of the knife blade is stored within a cavity in the knife handle.  
           [0005]    Unfortunately, with both liner locks and back lock locking mechanisms, it is possible for the locking apparatus to potentially become disengaged from the blade after excessive and continuous use. Further, the positioning of the liner lock and back lock are often difficult to locate with a user&#39;s fingers, and cannot be accessed on both a front and rear side of the knife handle. Additionally, these type of locking mechanisms require the use of a “stop pin”, which is positioned on a forward portion of the handle above the pivot pin of the blade, and proximate to an upper edge of the handle. The stop pin prevents the knife blade from over-rotating when the blade is in an extended position of use by directly contacting a heel portion of the blade.  
           [0006]    Thus, there is a need for an improved folding knife locking mechanism which is mechanically simplistic, uses a minimum number of components and is extremely reliable to prevent the inadvertent closure of the knife blade. There is an additional need for a locking mechanism which is positioned to allow quick and easy access by one or more of a user&#39;s fingers on both sides of the knife handle, and which eliminates the need for a stop pin.  
         SUMMARY OF THE INVENTION  
         [0007]    It is thus one aspect of the present invention to provide a blade locking mechanism which serves the dual purpose of locking a folding knife blade in an extended position of use, and simultaneously serves as a stop pin, thus eliminating the necessity of a secondary component. Thus, in one embodiment of the present invention a locking mechanism is provided which has an anvil with a lower surface and an upper surface which mainly engages the heel portion of the knife blade to prevent inadvertent closure, and over-extension of the knife blade.  
           [0008]    It is another aspect of the present invention to provide a locking mechanism for a folding knife or multi-tool which is positioned immediately opposite a user&#39;s thumb or fingers and which is thus immediately accessible for selective opening. Thus, in one embodiment of the present invention the lock release mechanism is positioned immediately adjacent to a user&#39;s thumb or finger, and may be accessed on both sides of a folding knife handle. Alternatively, the lock release mechanism is positioned along an upper edge of the knife handle, and is then held downward with hand pressure during use, thus making it substantially “fail safe” and incapable of opening while being used.  
           [0009]    It is a further aspect of the present invention to provide a locking mechanism which has a biasing means which continually biases the locking mechanism to secure the blade while it is in an extended position, and thus cannot be inadvertently closed. Thus, to release the blade the locking mechanism must be engaged by a user&#39;s thumb or finger and pushed in a predetermined direction by the user, thus making it substantially impossible for the knife locking mechanism to fail. Alternatively, the locking mechanism may be oriented in numerous different directions to accommodate certain handle and blade designs, and may be used without any type of biasing means. In these embodiments, the locking mechanism can be engaged or disengaged with the tang of the folding knife blade by means of gravity or by pressure from a user&#39;s fingers.  
           [0010]    It is yet another aspect of the present invention to provide a blade locking mechanism which is simplistic to use, cost effective to manufacture and requires a minimum number of components which are not susceptible to failure after repeated use. Thus, in one embodiment of the present invention a locking mechanism is provided which both locks the knife blade in an extended position of use, and also prevents overtravel, thus eliminating the stop pin.  
           [0011]    Thus, in one aspect of the present invention, a folding knife with an integral blade locking mechanism and stop pin are provided, comprising:  
           [0012]    a central body;  
           [0013]    an aperture extending through said central body;  
           [0014]    a pivot pin extending through said aperture and operably interconnected to a handle of the folding knife, wherein said central body rotates with respect to the handle;  
           [0015]    an anvil extending outwardly from said central body and adapted to engage a tang positioned on a heel end of a blade on the folding knife when the blade is in a first extended position of use;  
           [0016]    an overtravel surface positioned on a forward edge of said central body which is adapted to operably engage the heel end of the folding knife blade when the blade is in said first extended position of use;  
           [0017]    wherein when said central body is rotated, said anvil is disengaged from the tang of the blade and the knife blade is unrestricted to travel between said first extended position of use to a second closed position with a lower edge of the blade substantially enclosed within a cavity of the folding knife handle. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 is a front elevation view of one embodiment of the present invention showing a folding knife extended in a position of use with the front scale of the handle removed for clarity;  
         [0019]    [0019]FIG. 2 shows the folding knife of FIG. 1 in a closed position;  
         [0020]    [0020]FIG. 3 shows the folding knife of FIG. 1 in an intermediate position between a first extended position of use and a second closed position;  
         [0021]    [0021]FIG. 4 is a front elevation view of an alternative embodiment of the present invention and identifying a folding knife in an extended position of use with a biasing spring and locking lever, the front scale of the handle removed for clarity;  
         [0022]    [0022]FIG. 5 is a front elevation view of the embodiment shown in FIG. 4 with the blade in a closed position;  
         [0023]    [0023]FIG. 6 is a front elevation view the embodiment shown in FIG. 4 with the blade in an intermediate position;  
         [0024]    [0024]FIG. 7 is a front elevation view of the knife embodiment shown in FIG. 4 and further identifying a racheting mechanism associated with the folding lever and locking mechanism; and  
         [0025]    [0025]FIG. 8 is an expanded front elevation view of the locking mechanism and blade tang in one embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0026]    Referring now to the drawings, FIG. 1 is a front elevation view of one embodiment of the present invention and which depicts a folding knife  2  with a blade  6  in a first extended position of use. The front scale of the handle  4  is removed for clarity and to identify the various components of the locking mechanism  24 . More specifically, the folding knife  2  generally comprises a blade  6  which is rotatably interconnected to a handle  4 . The blade includes a front end  8 , blade heel end  10 , a blade upper edge  12 , and a blade lower edge  14  which is typically sharpened, as well as a blade tang  16  positioned proximate to the heel end  10 , and which engages the locking mechanism  24  of the present invention.  
         [0027]    In the embodiment shown in FIG. 1, the locking mechanism  24  generally comprises a locking anvil  26  which engages the blade tang  16 , and which further includes a blade overtravel surface  28  which is used to prevent the blade heel end  10  from overextending when the blade  6  is in an extended position of use as shown. This combined feature of the locking mechanism  24  eliminates the need for a stop pin. Additionally, and as shown in dotted lines, the blade locking mechanism  24  may be interconnected to a locking lever  32  which is engaged by a user&#39;s finger to alternatively lock and unlock the blade to allow the blade to rotate between a first extended position of use and a second closed position. As appreciated by one skilled in the art, the blade locking lever  32  may be comprised of any numerous variations of levers or slides which serve the purpose of rotating the locking anvil  26  around the locking mechanism pivot pin  30 .  
         [0028]    Referring now to FIG. 2, the folding knife  2  shown in FIG. 1 is further depicted with the blade in a second closed position. In this particular position, the blade lower edge  14  is located within a cavity in the blade handle  4 , and thus prevents a user from inadvertently being cut or injured. Further, the locking anvil  26  is shown engaged in a blade catch slot  40  which is used to substantially maintain the blade  6  in a closed position until finger pressure is applied to a blade aperture  42  or other opening device such as a thumb stud to allow the blade  6  to be rotated from the closed position to a first extended position of use as shown in FIG. 1.  
         [0029]    Referring now to FIG. 3, the folding knife  2  is depicted in an intermediate position between the first extended position of use and the second closed position. As the blade  6  rotates between the first extended position and second closed position, the locking anvil  26  is maintained in a position which allows rotation, yet when the blade becomes closed the locking anvil  26  engages the blade catch slot  40 . When the blade is fully extended, the locking anvil  26  engages the blade tang  16 , and is thus locked into position to prevent rotation. When pressure is applied to the blade, an upper edge  12  of the blade  6  is secured by the locking anvil  26  and thus prevented from inadvertently rotating.  
         [0030]    Referring now to FIGS.  4 - 6 , a front elevation view is provided of an alternative embodiment of the present invention, and further depicting a folding knife  2  shown in a first extended position of use (FIG. 4), an intermediate position of use (FIG. 6), and a closed position (FIG. 5). In this particular embodiment, a locking lever  32  is shown which has considerably more length than the embodiment shown in FIG. 1, and which is positioned along an upper edge of the handle  4  and which extends over a handle finger depression  38 . The handle finger depression  38  allows easy access to the locking lever  32 , and which is pulled upward to allow rotation of the blade  6  around the blade pivot pin  18 . As further shown in these drawings, the overtravel surface  28  of the blade is clearly identified and which engages a portion of the locking anvil  26  of the locking mechanism  24 . This overtravel surface  28  and the associated locking mechanism  24  prevents the blade from over-extending when force is applied to a blade lower edge  14 , and thus eliminates the need of a stop pin which is typically positioned between the blade tang  16  and locking mechanisms in a typical folding knife  2 . As further identified in FIGS.  4 - 6 , a biasing spring  34  is provided which maintains the locking lever  32  in a downward position until an upward force is applied to release the locking anvil  26  from the blade tang  16 . As further shown in FIG. 5, when the blade  6  is in a closed position the locking anvil  26  is positioned within the blade catch slot  40  and which retains the blade in a closed position until a downward force is applied to the blade  6  to promote rotation.  
         [0031]    Referring now to FIG. 7, the blade  6  is shown in an intermediate position of travel between a first extended position and a second closed position. More specifically, the ratcheting slot and pin  36  and their relative position during rotation of the blade are shown herein. Comparing FIGS. 6 and 7, when the locking lever  32  is pulled upwardly as shown in FIG. 6, the ratcheting pin is positioned in a lower portion of the slot, while in FIG. 7 when the locking lever  32  is positioned proximate to the knife handle, the ratcheting pin  36  is positioned in an upper portion of the ratcheting slot.  
         [0032]    Referring now to FIG. 8, an expanded view of the locking mechanism  24  of the present invention is provided in greater detail and with respect to a blade heel end  10 . This enlarged drawing shows the components of the locking mechanism  24 , with respect to the blade, and including the locking anvil  26  and the locking mechanism pivot pin  30 . The blade heel end  10  further comprises a blade tang  16  which engages the locking anvil  26  when the blade is in a first extended position of use. Furthermore, the blade overtravel surface  28  is shown contacting an upper portion of the anvil  26  to prevent the blade  6  from overextending when the blade is in a first extended position of use. Thus, the dual role of the locking mechanism  24  can clearly be shown in FIG. 8, wherein the blade is prevented from overextending due to the contact between the overtravel surface  28  and the upper portion of the locking anvil  26 , and is further prevented from closing due to the contact between a lower portion of the locking anvil  26  and the blade tang  16 .  
         [0033]    For clarity purposes, a list of components and associated numbering shown in the attached drawings are provided herein:  
                                             #   Component                                2   Folding knife       4   Handle       6   Blade       8   Blade front end       10   Blade heel end       12   Blade upper edge       14   Blade lower edge       16   Blade tang       18   Blade pivot pin       20   Handle front end       22   Handle rear end       24   Locking mechanism       26   Locking anvil       28   Overtravel surface       30   Locking mechanism pivot pin       32   Locking lever       34   Biasing spring       36   Ratcheting slot and pin       38   Handle finger depression       40   Blade catch slot                  
 
         [0034]    While an effort has been made to describe various alternatives to the preferred embodiment, other alternatives will readily come to mind to those skilled in the art. Therefore, it should be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. Present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not intended to be limited to the details given herein.