Abstract:
A folding knife locking mechanism is provided which prevents the inadvertent closure of a knife blade by utilizing a releasable tang which is compressed between the heel end of the folding knife blade and a stop pin.

Description:
[0001]    This application claims priority of U.S. provisional patent application Ser. No. 60/184,220 having a filing date of Feb. 23, 2000, and is incorporated herein in its entirety by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention is related to cutting instruments, and more specifically folding knives with locking mechanisms to prevent the inadvertent closure of a knife blade associated with the folding knife.  
         BACKGROUND OF THE INVENTION  
         [0003]    Cutting instruments have been used for centuries by craftsmen, hunters, and others requiring a sharp cutting instrument. More recently, fixed length knives have been replaced with popular folding knives which generally have two positions. In a first extended position of use, the folding knife cutting blade is extended to expose the blade cutting edge and permit cutting therein. In a second closed position, the cutting edge of the blade is stored within a cavity in the handle portion of the knife, thus preventing the blade from being exposed and providing a cutting instrument which is much shorter in length than a typical fixed blade knife. Although these types of knives are extremely convenient, they can potentially become dangerous if the cutting blade does not have a locking mechanism to securely keep the knife blade in the first extended position of use. Likewise, it is often convenient to have a locking mechanism or some form of frictional ball detente apparatus to prevent the knife from inadvertently opening when the knife blade is in the second closed position.  
           [0004]    Numerous attempts have been made to provide locking mechanisms which prevent a knife blade from inadvertently opening, closing, or both. One of the most commonly known locking mechanisms is a “back lock.” The back lock uses a longitudinal length of rigid material, most commonly stainless steel, which pivots about a pivot point near the forward portion of the back lock. By applying pressure to a rearward portion of the locking mechanism, the locking mechanism rotates about the pivot point and releases a tang engagement mechanism from the heel portion of the knife blade. As the heel portion is released, the knife blade is released from the locking mechanism and is allowed to rotate from the first extended position to the second closed position. Although convenient to use, the back lock is not particularly strong and has a tendency to fail when excessive pressure is applied to the upper edge of the knife blade.  
           [0005]    Another type of locking mechanism commonly used for folding knives is generally referred to as a “liner lock”. A liner lock generally comprises a metallic leaf spring which is biased and positioned within the cavity of a knife handle and interconnected to one of the scales which comprises the knife handle. Upon opening of the knife blade to a first extended position of use, the forward or tang end of the leaf spring extends outwardly from the scale and behind the heel portion of the knife blade, thus preventing the knife blade from being closed without pushing the leaf spring liner lock to the side of the heel end of the knife blade, thus allowing rotation of the knife blade to the second closed position. Although simplistic in design, liner locks can potentially fail if excessive force is applied to the upper edge of the knife blade. During failure, the liner lock has a tendency to bow or otherwise deform, due to the extended length of the liner lock and the thin nature of the material required to fit within the knife handle cavity.  
           [0006]    Although there are other types of locking mechanisms used to prevent the inadvertent closure of a folding knife blade, none are simplistic to use, inexpensive to manufacture and are essentially fail-proof. Thus, there is a need for a type of folding knife locking mechanism which is simplistic to use, inexpensive to manufacture, and provides substantial strength to prevent any inadvertent failure.  
         SUMMARY OF THE INVENTION  
         [0007]    It is thus an object of the present invention to provide a folding knife locking mechanism which is substantially non-defeatable when pressure is applied to the back edge of the knife blade when the blade is in an extended position of use. It is a further object of the present invention that the folding knife locking mechanism be designed to use a minimum number of components, thus making the locking mechanism inexpensive to manufacture, simplistic in design, and encompassing a variety of different embodiments for use with a number of different folding knife designs.  
           [0008]    It is a further object of the present invention to provide a locking mechanism which utilizes a compressive force generated over a very short distance between the blade stop pin and the heel end of the blade. This geometric configuration substantially prevents the locking mechanism from failing during use.  
           [0009]    Thus, in one aspect of the present invention, a locking mechanism is provided which positions a tang between the stop pin of the knife handle and anvil portion of the heel end of the knife blade. When a force is applied to the upper edge of the knife blade, the tang of the knife locking mechanism is compressed between the anvil end of the heel end of the knife blade and the stop pin. This unique positioning of the tang allows the locking mechanism to withstand substantial forces.  
           [0010]    Thus, in one particular aspect or embodiment of the present invention, a folding knife with a compression locking mechanism is provided which generally comprises:  
           [0011]    a handle having a front end, a rear end and a cavity defined therebetween;  
           [0012]    a knife blade having a front end, a heel end with an anvil, a cutting edge and an upper edge, said heel end rotatably interconnected to said front end of said handle wherein said knife blade travels between a first extended position of use and a second closed position with said knife blade cutting edge positioned within said handle cavity;  
           [0013]    a stop pin positioned within an upper edge of said handle cavity for engaging an upper portion of said heel end of said blade when said knife blade is in said first extended position of use;  
           [0014]    a locking mechanism positioned proximate to said handle cavity, said locking mechanism comprising a tang releasably positioned between said anvil of said blade and said stop pin when said knife blade is in said first extended position of use, wherein when pressure is applied downward on said upper edge of said knife blade, said tang is compressed between said blade anvil and said stop pin to prevent inadvertent closure of said knife blade.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 is a front elevation view of a folding knife with a compression locking mechanism, the front scale of the handle being removed for clarity;  
         [0016]    [0016]FIG. 2 is a top plan view of the folding knife of FIG. 1 with the stop pin removed for clarity in the upper drawing;  
         [0017]    [0017]FIG. 3 is a front elevation view of the folding knife of FIG. 1 with both the front and the rear scale removed for clarity;  
         [0018]    [0018]FIG. 4 is a top plan view of the folding knife of FIG. 3 with the knife blade in a closed position;  
         [0019]    [0019]FIG. 5 is a rear elevation view of the knife in FIG. 4;  
         [0020]    [0020]FIG. 6 is a front elevation view of the knife in FIG. 4;  
         [0021]    [0021]FIG. 7 is a front elevation view of a folding knife with an alternative embodiment of the compression locking mechanism;  
         [0022]    [0022]FIG. 8 is a top plan view of the knife shown in FIG. 7 with the stop pin removed for illustration purposes in the upper drawing;  
         [0023]    [0023]FIG. 9 is a front elevation view of a folding knife with the compression locking mechanism having a shape essentially the same as a knife handle, and with the blade shown in an extended position of use and both the front scale and rear scale removed for clarity;  
         [0024]    [0024]FIG. 10 is a top plan view of the knife of FIG. 9 with the blade in a closed position;  
         [0025]    [0025]FIG. 11 is a rear elevation view of the knife of FIG. 10;  
         [0026]    [0026]FIG. 12 is a front elevation view of the knife in FIG. 10;  
         [0027]    [0027]FIG. 13 is a top plan view of a liner lock knife locking mechanism shown in contact with the heel end of a knife blade;  
         [0028]    [0028]FIG. 14 is a top plan view of an alternative push button mechanism used for releasing the folding knife compression locking mechanism;  
         [0029]    [0029]FIG. 15 is a top plan view of an alternative compression lock swivel release mechanism used for releasing the locking mechanism of the folding knife;  
         [0030]    [0030]FIG. 16 is a top plan view of an alternative rotating lock release mechanism for releasing the compression locking device; and  
         [0031]    [0031]FIG. 17 is a top plan view of an alternative sliding release mechanism used to release the compression locking mechanism of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0032]    Referring now to the drawings, FIG. 1 represents one particular embodiment of the present invention and generally depicts a folding knife in a first extended position of use with the knife blade extended for use. In general, the folding knife  2  comprises a blade  4  rotatably interconnected to a handle  14  by means of a rotation pin  28  that extends through an aperture in the knife blade  4 . The folding knife  2  is thus able to be used with the blade  4  in a first extended position of use as shown, and subsequently closed to a second position of non-use wherein the blade cutting edge  6  is positioned within the knife handle  14 . The knife handle is generally comprised of a rear scale  16  and a front scale  18  which defines a cavity  58  for receiving the knife blade  4 . A stop pin  12  is typically interconnected to the handle  14  near the upper edge and extends within the cavity  58 . The stop pin  12  is typically provided to prevent the knife blade  4  from overtraveling when the blade is in a first extended position of use and force is applied to the cutting edge  6  of the blade  4 . The knife blade  4  is generally comprised of a blade cutting edge  6 , a blade upper edge  8 , and a blade heel end  40  which further includes a blade anvil  20 .  
         [0033]    In one embodiment of the present invention, a locking mechanism  22  as seen in FIG. 1 is provided to secure the knife blade  4  in a first extended position of use. Generally, the locking mechanism comprises a locking mechanism tang  24  positioned at the forward end of the locking mechanism  22 , and which is interconnected to either the rear scale  16  or front scale  18  by means of one or more attachment pins  30 . Alternatively, the locking mechanism  22  can be interconnected to the knife handle by flues, adhesives or epoxies. The upper portion of the locking mechanism  22  comprises a thumb ramp  26  which is used to contact a user&#39;s thumb to engage and disengage the locking mechanism tang  24 .  
         [0034]    As seen in FIG. 1, the locking mechanism  22  works by the tang  24  being positioned between the blade anvil  20  and the stop pin  12  when the blade  4  is in a first extended position of use. Thus, when a force is provided downward on the blade upper edge  8 , the tang  24  of the locking mechanism is compressed between the stop pin  12  and the blade anvil  20 . This positioning of the tang  24  causes a compressive force between the stop pin  12  and anvil  20  when a force is applied to the upper end of the blade, and thus prevents the knife blade from rotating downward and potentially cutting a user&#39;s fingers. With this improved design, the overall strength of the knife locking mechanism is dictated by the size, i.e. width and/or height of the locking mechanism tang  24 , and which can inherently be made to withstand substantially forces which are not possible with conventional folding knife locking mechanisms.  
         [0035]    The locking mechanism  22  is generally comprised of a metallic material such as stainless steel. However, other materials resistant to compressive forces could be used for the same purpose. To disengage the tang  24  from between the stop pin  12  and the anvil  20 , the locking mechanism  22  is pushed in a normal direction toward the adjacent scale by means of providing a lateral pressure to the thumb ramp  26 . This removes the position of the tang  24  from between the stop pin  12  and anvil  20 . As stated before, the locking mechanism could be provided adjacent either the front scale  18  or the rear scale  16  depending on the preference of the manufacturer and/or user.  
         [0036]    Referring now to FIG. 2, two top plan views are shown which more clearly identify the locking mechanism  22 , the blade upper edge  8 , and more specifically the locking mechanism tang  24  engaged to the blade anvil  20 . The upper drawing of FIG. 2 shows the positioning of the tang  24  and the blade anvil  20  with the stop pin  12  removed for clarity. As seen in both FIG. 1 and the lower drawing in FIG. 2, the stop pin  12  is generally positioned directly above the tang  24 , and thus provides the necessary obstacle to prevent the tang  24  from being driven upward when a significant force is applied to the blade upper edge  8 . Alternatively, the stop pin could be an extension of the locking mechanism prevent overtravel by the knife blade  4 .  
         [0037]    Referring now to FIG. 3, the folding knife of FIG. 1 is shown with the rear scale  16  removed for clarity. In this particular drawing, the locking mechanism  22  can be clearly shown engaged to the knife blade anvil  20 . In an additional feature shown in FIG. 3, a blade lock detente  56  is provided in the blade heel end  40  which allows the folding knife blade to be in a closed position without inadvertently opening by means of the resistance provided by the locking mechanism  22  being engaged with the lock detente  56 . Alternatively, a ball detente type of mechanism could be used for the same purpose. Thus, the locking mechanism  22  can be used both to prevent the knife blade  4  from being inadvertently closed when in a first extended position of use as shown in FIG. 3, and also from being opened when in a closed position as shown in FIGS. 4, 5 and  6 .  
         [0038]    More specifically, and as seen in FIGS.  4 - 5 , when the knife blade  4  is in a closed position of use, the forward end of the tang  24  becomes engaged with the blade lock detente  56  which is generally a slot or notch provided in the blade heel end  40 . The resistance provided by the biasing of the compression locking mechanism  22  thus holds the blade  4  in a closed position until a slight pressure is applied downward on the knife blade  4 , and thus pulling the blade away from the locking mechanism  22 .  
         [0039]    Referring now to FIGS.  5 - 6 , FIG. 6 is a front elevation view of the knife shown in FIG. 3 with the blade in a closed position, while FIG. 5 is a rear elevation view of the same embodiment of the present invention with the rear scale  16  removed for clarity. As seen in FIG. 5, the blade lock detente  56  is shown engaged with the compression lock tang  24  which holds the blade  4  in the closed position. Thus, when the knife blade  4  is pulled downward and away from the locking mechanism  22 , a restrictive force between the locking mechanism  22  and the blade lock detente  56  is provided until the locking mechanism is pushed to the side of the blade heel end  40 .  
         [0040]    Referring now to FIGS. 7 and 8, an alternative embodiment of the present invention is provided. In this particular design, the locking tang  24  has a slightly arcuate shape on a forward end, and has the thumb ramp  26  positioned on the lower end of the knife handle  14  as opposed to the upper end as shown in FIG. 1. Furthermore, the compression locking mechanism  22  and associated locking tang  24  comprises one of the scales of the knife handle  14 . Thus, the compression locking mechanism  22  is integrally interconnected to the handle, and thus eliminates the necessity to manufacture and assemble an independent locking mechanism which is interconnected to one of the scales of the handle  14 .  
         [0041]    To release the tang  24  from the blade anvil  20  of the knife blade, the thumb ramp  26  is moved outward to allow the tang  24  to disengage from the blade heel end  40 , and thus permit the knife to rotate from a first extended position of use as shown to a second closed position. As additionally seen in FIG. 7, a more typical type of ball detente  38  is provided which holds the knife blade  4  in the second closed position of use until the ball portion of the detente  38  is released from the female portion of the ball detente  38  which is shown on the heel end of the knife blade  4 . As appreciated by one skilled in the art, the ball portion of the detente  38  may be provided on the heel portion of the blade, with the female portion of the ball detente provided in the tang portion of the compression lock. Referring now to FIG. 8, a top plan view is provided of the knife of FIG. 7 and showing the tang  24  engaged to the blade anvil  20 . In the upper view of FIG. 8, the stop pin  12  is removed for clarity purposes, whereas in the bottom view the stop pin is shown.  
         [0042]    Referring now to FIGS.  9 - 12 , the invention of FIG. 8 is shown however the compression locking mechanism  22  is shown having a shape which is similar to the shape of the handle  14 . Thus, in this embodiment, no additional handle piece, i.e., front scale  18  and rear scale  16 , would be required to provide a functional folding knife with a compression locking mechanism. However, more typically various laminated or ornamental types of handle scales would be utilized by gluing and/or attaching the handle portion to the blade locking mechanism  22 . In all other respects, the locking mechanism  22  and associated tang  24  are used in the same way as the compression locking mechanism  22  shown in the earlier drawings. FIG. 10 represents a top plan view of the invention shown in FIG. 10, while FIG. 11 is a rear elevation view with the knife blade  4  in a closed position, while FIG. 12 is a front elevation view of the invention shown in FIG. 9 with the blade  4  in a closed position.  
         [0043]    Referring now to FIG. 13, this drawing depicts a top elevation view of a novel type of “liner lock” locking mechanism. As seen in this particular drawing, the liner lock  22  engages the blade heel end  40  to prevent the blade  4  from closing. However, there is one novel feature that is “progressive” liner lock that is not seen in the prior art. More specifically, there is a radius point of the blade heel end  42  which serves to prevent the locking mechanism  22  from inadvertently sliding and moving beyond the blade heel end  40 . Although subtle, this “arcuate” curved portion of the liner lock is a very important feature of the radius point  42  of the blade heel end  40  is critical to prevent the locking mechanism  22  from inadvertently disengaging from the blade heel end  40 .  
         [0044]    [0044]FIG. 14 is a top elevation view of an alternative release mechanism used in conjunction with the locking mechanism  22  of the present invention. More specifically, a lock push button  44  is provided which engages the lateral surface of the locking mechanism  22 . When the blade  4  is desired to be released from the first extended position of use, pressure is merely provided to the push button  44  which engages the lateral side of the locking mechanism  22 , and pushes the tang  24  to the side of the blade and thus allowing the blade to rotate downward. The lock push button  44  would typically be positioned in the middle of the knife handle  14  opposite the locking  24 , although it is contemplated that other positions would be equally effective.  
         [0045]    As shown in FIG. 15, an alternative embodiment of the present invention is provided. More specifically, a lock swivel release  46  is provided which has a shortened locking mechanism  22 , but still incorporates the locking tang  24  which engages the blade anvil  20 . To disengage the locking mechanism  22  from the blade heel end  40 , an outward pressure is provided to the upper portion of the lock swivel release  46  which disengages the tang  24  from the blade anvil  20 .  
         [0046]    Referring now to FIG. 16, another alternative embodiment of the present invention is shown. More specifically, a rotating lock mechanism  48  is provided which allows the tang to swivel in and out between the blade anvil  20  and the stop pin  12 . Thus as depicted by the arrow in this particular embodiment which identifies the respective direction of movement, when thumb pressure is applied to any part of the upper portion of the rotating lock mechanism  48  in a direction substantially normal to the longitudinal length of the handle, the tang  24  will become disengaged from the blade anvil  20 .  
         [0047]    Referring now to FIG. 17, yet another alternative embodiment of the present locking mechanism is shown. More specifically a sliding button release  50  is shown which allows the locking mechanism tang  24  to be slidingly engaged between the blade anvil  20  and the stop pin  12 . Thus in this particular embodiment, to disengage the locking mechanism from the blade  4 , the sliding release  50  is drawn rearward away from the knife blade  4  which removes the locking tang  24  from between the stop pin  12  and the blade anvil  20 .  
         [0048]    To provide further clarity to the detailed description provided herein in the associated drawings, the following list of components and associated numbering are provided as follows:  
                                   Component No.   Component                   02   Folding Knife       04   Blade       06   Blade Cutting Edge       08   Blade Upper Edge       10   Blade Aperture       12   Stop Pin       14   Handle       16   Rear Scale       18   Front Scale       20   Blade Anvil       22   Locking Mechanism       24   Locking Mechanism Tang       26   Thumb Ramp       28   Rotation Pin       30   Lock Attachment Pin       32   Handle Upper Edge       34   Handle Lower Edge       36   Locking Mechanism Aperture       38   Ball Detente       40   Blade Heel End       42   Radius Point Of Blade Heel End       44   Lock Push Button       46   Lock Swivel Release       48   Rotating Lock Mechanism       50   Sliding Button Release       56   Blade Lock Detente       58   Handle Cavity                  
 
         [0049]    The foregoing description of the present invention has been presented for illustration and description purposes. However, the description is not intended to limit the invention to only the form as disclosed herein. Consequently, variations and modifications commensurate with the above teachings and skill and knowledge of the relevant art are within the scope of the present invention. The embodiments described herein above are further intended to explain best modes of practicing the invention and to enable others skilled in the art to utilize the invention in such a manner, or include other embodiments with various modifications as required by the particular application(s) or use(s) of the present invention. Thus, it is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.