Abstract:
This invention relates to a mechanism in a folding knife that urges the blade to move to an open and alternatively to a closed position. The knife generally consists of a blade having a tang extending outwardly from the blade; a handle having at least one recessed portion; a bar pivotally connecting the tang and the handle; and a bias element engaging the blade wherein the bias element is housed within the recessed portion of the handle. Generally, in the present invention, the blade must be moved manually a certain distance whereupon the mechanism serves to complete the movement of the blade without the application of further outside force by the user.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 09/096,870, filed Jun. 11, 1998 now U.S. Pat. No. 6,145,202 for AN OPENING AND CLOSING ASSISTING MECHANISM FOR A FOLDING KNIFE, which claims the benefit of priority of U.S. Provisional Patent Application Ser. No. 60/077,390, filed Mar. 10, 1998 for AN OPENING AND CLOSING ASSISTING MECHANISM FOR A FOLDING KNIFE. These applications are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a mechanism in a folding knife that urges the blade to move to an open and alternatively to a closed position. Generally, in the present invention, the blade must be moved manually a certain distance, whereupon the mechanism serves to complete the movement of the blade without the application of further outside force by the user. 
     In the folding knife and cutlery industry, there typically is provided a folding knife having a housing or handle for supporting the blade in the open position and for receiving the blade in the closed position. It also is known generally to cause the blade of the knife to be locked when in the open position. An example of such locking mechanism is found in Neely, U.S. Pat. No. 5,060,379 and Wiethoff, U.S. Pat. No. 4,404,748. The mechanism of the present invention overcomes the various deficiencies of the folding knives and opening and closing mechanisms presently in the knife and cutlery industry by providing positive opening and closing assistance while enabling such opening and closing to be performed or carried out with only a single hand of the user, to the advantage of the general public, but especially to persons who experience difficulty in using two hands to open a knife, whether such arcuity is caused by physical, mental, or safety reasons. 
     SUMMARY OF THE INVENTION 
     The present invention generally provides for a folding knife generally comprising a blade, a handle for receiving and supporting the blade, and a mechanism located within the handle that communicates with the blade and provides positive assistance for opening and closing of the blade. The mechanism generally includes a bias element in communication with an arcuate slot in the tang of the blade. A thumb bob or stud may be attached to the blade for ease of opening and a locking means, such as a liner lock, may be provided within the handle of said knife for locking the blade in the open position. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 of the drawings is a side view of the knife embodying the present invention; 
     FIG. 2 is a top view of the knife in the closed position; 
     FIG. 3 is a side view of the knife in the closed position displaying the preferred assisting mechanism within the handle with portions broken away better to illustrate the construction of the knife; 
     FIG. 4 is a side view of the knife in the open position displaying the preferred assisting mechanism within the handle, with portions broken away better to illustrate the construction or the knife; 
     FIG. 5 is an enlarged partial top view of the knife in the open position, taken along the lines  5 , 5  of FIG. 4; 
     FIG. 6 is an enlarged sectional view of an alternate embodiment of the knife, taken along line  6 , 6  of FIG. 5; 
     FIG. 7 is an enlarged sectional view of the knife, taken along lines  7 , 7  of FIG. 3; 
     FIG. 8 is a modified side view of the knife in the closed position of an alternate embodiment of the present invention; 
     FIG. 9 is a fragmentary side view of the knife in a closed position of a second alternate embodiment; 
     FIG. 10 is a fragmentary side view of an alternate embodiment in the open position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1-7, the knife  10  generally is composed of a handle or casing  11 , a mechanism  12  held within the handle or casing and a blade  13 . 
     The handle has side parts  14 ,  14   a,  each with a tapered rear end  15  and a rounded front end  16 . Each side has an interior lining  17 ,  17   a  which communicates with the outer edge of the interior side of parts  14 ,  14   a.  The interior linings are connected to a central casing member  18  which communicates with the interior linings bottom and rear edges to form a central cavity  19 . The interior of the central casing  18  is curved according to the shape of the blade and forms a stop for the blade when the blade is placed in the closed position. Each side part and lining has a plurality of threaded holes  21  that receive screws which secure the sides together and an opening for a pivot bar  22 . The interior linings are joined near the front end  16  of the handle by a stop bar  23 . 
     Side part  14   a  has a recessed portion  24  that does not communicate with the interior lining, and side part  14  has a recess  25 . A portion of interior lining  17 , indicated in FIG. 2 as lining portion  26 , is separate from the lining  17  at the front end of the handle and is displaceable. Portion  26  is biased like a leaf spring so that the lining portion  26  extends into the central opening  19  of the handle when the blade is placed in the open position, as shown in FIG.  5 . The forward end  27  of the displaceable lining portion  26  communicates with the tang  28  of the blade when the blade is in the open position so as to prevent folding of the blade into the central cavity  19  because free end  27  is in the path of travel of tang  28 , preventing pivoting of blade  13 . 
     A side view of a lining portion  126  is shown in FIG. 6, as part of an alternative embodiment of the present knife, in which the moveable lining portion  126  is formed in interior lining  17   a,  on the same side of the handle as recessed portion  24 . For both embodiments, the recess adjacent the moveable lining portion  26  or  126  allows free end  27  or  127  to be pressed manually so that free end  27  or  127  is completely out of the path of travel of tang  28 , allowing following of the blade back into the central cavity  19 . 
     The recessed portion  24  houses a mechanism  12  generally composed of a bias element  29  that is operatively connected to handle  11  through a first groove  30  formed in a back strap  41  or like structure as shown in FIGS. 3 and 4. First groove  30  may also be formed in interior lining  17   a,  as shown in FIG.  5 . Bias element  29  also is operatively connected to blade  13  through a second groove  31 . The bias element is generally the length of the handle and has a bent end  29   a  and a second bent end  29   b.  The first and second ends are turned at approximately 90° from the body  34  of the bias element. The first end  29   a  is received within the first groove  30 . The second end  29   b  is located near the front  16  of the handle and is received within an arcuate second groove  31  in the interior lining  17  and a corresponding hole in the tang  28  of the blade  13 . 
     Stop bar  23  extends across the front end of the central cavity  19 . The stop bar fits within a recess  20  in the tang of the blade when the blade is in the closed position and communicates with the rear end  43  of the tang when the blade is in the open position. 
     The blade has a distal end  35  and a proximal end  36 , with tang  28  adjacent to the proximal end of the blade. Thumb bob  37  is mounted on a side of the blade near the proximal end and outside the tang area. The tang has an arcuate slot corresponding to groove  31  capable of receiving a bent front end of the biased element  29 , and a recessed area generally conforming to the stop bar, and a hole for receiving a pivot bar  22 . 
     In operation, the knife in a closed position is grasped with the rear end  15  of the handle oriented towards the holder&#39;s wrist and the bottom  38  of the handle resting in the palm resulting in placement of the thumb bob  37  in close proximity to the holder&#39;s thumb. Pressure is applied to the thumb bob  37  upwards in the direction away from the palm, causing the blade to rotate clockwise about the pivot bar  22  and exit the central cavity  19 . As the blade is lifted out of the central cavity  19 , the bias element  29  is moved past an equilibrium point, after which the bias element  29  exerts an opening force on the blade  13 . When the end  29   b  reaches a certain critical angle in the arcuate groove  31 , the tension of the bias element  29  causes the end  29   b  to quickly slide towards the end  32  of the arcuate slot, thereby causing the blade to extend to the full open position. Stop bar  23  communicates with the rear end  43  of the tang to prevent overextension of the blade. When the blade is in the fully extended position, the front end  29   b  of the bias element rests at the far end  32  of the arcuate groove and the rear end  29   a  of the bias element is positioned at the front end  40  of the rear groove  30 . When the blade clears the moveable lining, the free end  27  of the lining free end  27  extends into the central cavity and becomes lodged against the rear end  43  of the tang, thereby preventing the blade from closing. 
     To close the knife, pressure is applied to the moveable free end  27  of interior lining  17 , dislodging the end of the lining from the tang, placing the moveable lining in linear arrangement with the lining  17 . The blade then is rotated counterclockwise about the pivot bar  22  towards the central cavity  19 , causing the front bias element end  29   b  to slide toward the rear  33  of the arcuate groove  31 . When the front bias element end  29   b  reaches a certain critical angle in the arcuate groove  31 , the rear end  29   a  of the bias element travels to the rear end  42  of the groove  30 , thereby permitting the front end  29   b  of the bias element to travel to the rear bottom position  33 , causing the blade to fold into the central cavity. In the closed position, the bottom edge of the blade rests against the central casing  18  and the stop bar  23  is received within the recessed  20  of the tang, preventing further movement of the blade in the closing direction. 
     It will be appreciated that the mechanism provides positive pressure that facilitates movement of the blade, requiring only limited outside assistance by the user. The amount of outside assistance required to open and close the blade depends upon the angle of the arcuate groove, the length of end positioning of the first groove and the resilience of the bias element. 
     The bias element can be a material such as a spring, wire or equivalent thereof as shown in each of FIGS. 2-6 and  8 - 10 . Furthermore, the bias element or spring may include an integral pushrod as shown in FIGS. 3-6,  9  and  10 . As seen spring, wire or equivalent thereof and may include an integral pushrod as shown in FIG.  3 . As seen in the various depicted embodiments, the spring or bias element may be bent in a variety of ways. For example, as seen in FIGS. 3 and 4, the spring or bias element may include a simple bend formed between the opposed ends of the spring or bias element. The simple bend may be 90° and, more particularly, may be approximately 120°, as seen in FIG.  4 . FIGS. 9 and 10 show that the spring or bias element may have a coiled bend instead of a simple bend. The coiled bend may be 360° or greater, as revealed by FIGS. 9 and 10. For example, the coiled bend shown in FIG. 10 is approximately 480°. The preferred element for the spring or bias element is 0.062 music wire. 
     In alternative embodiments, the bias element can be a combination of a spring and a push rod, a coiled wire, or similar means. Referring to FIG. 8, the bias element consists of push rod  47  and helical spring  46  which is housed within longitudinal slot  45  defined between interior lining  17   a  and a recess in side part  14   a,  similar to the way in which bias element  29  is housed in the embodiments shown in FIGS. 1-6. Referring to FIGS. 9 and 10, bias element  29  consists of a wire wrapped or coiled about a circular member  49 . Other embodiments may be possible based upon the principles disclosed herein. Moreover, the shape of the tang may be modified according to known designs. 
     In all embodiments, the liner log may be changed to be a lockback or other known locking mechanism. Moreover, the blade may have a thumb bob on both sides of the blade, and the dual thumb bobs may serve as a stop for the blade when in the closed position. From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to this structure. It will be understood that certain features and some combinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. 
     Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.