Patent Abstract:
The present disclosure concerns embodiments of a folding knife having a locking mechanism for locking a blade in open and/or closed positions. The locking mechanism a first locking element on the blade and a corresponding second locking element on the handle that is adapted to engage the first locking element when the blade is in open and/or closed positions. The blade can be mounted on a leaf spring in the handle for pivotal movement relative to the handle between the open and closed positions. The leaf spring functions to support the blade and provide a biasing force that resiliently biases in a direction laterally toward the second locking element on the handle.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims the benefit of U.S. Provisional Application No. 61/182,225, filed May 29, 2009, which is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present application concerns a folding knife, and more specifically, a locking mechanism for a folding knife. 
       BACKGROUND 
       [0003]    Various types of folding knives having push buttons for unlocking a blade from a locked position are known. Such knives typically are complicated and require a relatively large number of parts. One example is disclosed in U.S. Pat. No. 4,148,140, which discloses a ball latch mechanism that can lock the blade in one of several positions. What is needed is a much simpler locking mechanism for a folding knife having a push button or similar mechanism for disengaging the locking mechanism. 
       SUMMARY 
       [0004]    The present disclosure concerns embodiments of a folding knife having a locking mechanism for locking a blade in open and/or closed positions. The locking mechanism comprises a first locking element on the blade and a corresponding second locking element on the handle that is adapted to engage the first locking element when the blade is in open and/or closed positions. The first locking element can be, for example, one or more locking projections that extend laterally from a side of the blade tang. The second locking element can be one or more locking notches that are sized to receive the locking projections when the blade is in open and/or closed positions. 
         [0005]    The blade can be mounted on a leaf spring in the handle for pivotal movement relative to the handle between the open and closed positions. The leaf spring functions to support the blade and provide a biasing force that resiliently biases in a direction laterally toward the second locking element on the handle. The leaf spring causes the first locking element to engage the second locking element when the blade is pivoted to the open position and/or when the blade is pivoted to the closed position. The blade can be released from being locked in the open or closed positions by applying manual pressure to the blade against the biasing force of the leaf spring to move the first locking element out of engagement with the second locking element. The blade can have a button or projection that extends laterally from one side of the blade and has an exposed end surface at one side of the handle that can be pressed inwardly to move the first locking element out of engagement with the second locking element. 
         [0006]    In one representative embodiment, a folding knife comprises a handle and a blade. The blade has a tang that is pivotably connected to the handle and is pivotable relative to the handle about a pivot axis between a closed position and an open position. The tang comprises a laterally extending projection and at least one laterally extending locking element. The handle comprises first and second, laterally spaced side portions, the first side portion comprising an aperture and at least one locking notch in communication with the aperture. The projection of the blade tang extends laterally into the aperture such that the projection can rotate within the aperture when the blade is pivoted between its open and closed positions. The second side portion comprises a leaf spring having a free end portion that is resiliently biased toward the first side portion. The free end portion pivotably supports the blade tang by a pivot element extending through the blade tang and the free end portion. The free end portion exerts a biasing force laterally against the blade such that when the blade is pivoted to its open position, the biasing force urges the blade into an open and locked position in which the locking element on the blade extends into and engages the locking notch. The blade can be released from the open and locked position by manually moving the blade laterally against the biasing force to move the locking element out of engagement with the locking notch. 
         [0007]    In another representative embodiment, a folding knife comprises a handle and a blade having a tang that is pivotably connected to the handle. The blade is pivotable relative to the handle about a pivot axis between a closed position and an open position. The tang has at least a first locking element. The handle comprises first and second, laterally spaced side portions, the first side portion comprising at least a second locking element adapted to engage the first locking element when the blade is pivoted to its open position. The second side portion comprises a leaf spring having a free end portion that supports the blade tang for pivoting movement of the blade. The free end portion is configured to apply a biasing force that urges the blade toward the second side portion such that when the blade is pivoted to its open position, the biasing force causes the blade to move toward the second side portion and cause the first locking element to engage the second locking element so as to lock the blade in the open position. 
         [0008]    In another representative embodiment, a folding knife comprises a handle and a blade having a tang that is pivotably connected to the handle. The blade is pivotable relative to the handle about a pivot axis between a closed position and an open position. The tang has first locking means. The handle comprises a leaf spring having a free end portion that supports the blade tang for pivoting movement of the blade. The handle further comprises second locking means for engaging the first locking means when the blade is in its open position. The free end portion of the leaf spring is configured to apply a biasing force against the blade such that when the blade is pivoted to its open position, the biasing force causes the blade to move laterally toward the second locking means to cause the first locking means to engage the second locking means so as to lock the blade in the open position. 
         [0009]    The foregoing and other features and advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a perspective, exploded view of a folding knife, according to one embodiment. 
           [0011]      FIG. 2  is a perspective view of the folding knife of  FIG. 1 . 
           [0012]      FIG. 3  is a perspective view of the blade of the folding knife of  FIG. 1 . 
           [0013]      FIG. 4  is side view of the folding knife of  FIG. 1  shown with one side of the handle removed for purposes of illustration. 
           [0014]      FIG. 5  shows the opposite side of the folding knife shown in  FIG. 4 . 
           [0015]      FIG. 6  is a side view of one of the frame portions of the folding knife of  FIG. 1  having an integral leaf spring and belt clip. 
           [0016]      FIG. 7  is a top plan view of the frame portion shown in  FIG. 6 . 
           [0017]      FIG. 8  is a side view of the folding knife of  FIG. 1  shown with the blade in the open position. 
           [0018]      FIG. 9  is a side view of the folding knife of  FIG. 1  shown with the blade in the open position. 
           [0019]      FIG. 10  is a top plan view of the folding knife of  FIG. 1  shown with the blade in the open position. 
           [0020]      FIG. 11  is a bottom plan view of the folding knife of  FIG. 1  shown with the blade in the open position. 
           [0021]      FIG. 12  is an exploded view of a blade and an optional push button that is connected to a side of the blade. 
           [0022]      FIG. 13  is a side view of an alternative embodiment of a frame portion having an integral leaf spring for supporting the blade. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Referring to the drawings, a folding knife  10 , according to one embodiment, comprises a handle  12  and a knife blade  14  pivotably connected to the handle  12 . The blade is pivotable relative to the handle between a closed position for storing the blade ( FIG. 8 ) and an open position for using the blade ( FIG. 9 ). The handle  12  comprises a first frame portion  16  (also referred to as a first side portion) and a second frame portion  18  (also referred to a second side portion) separated by a spacer, or spline,  20 . Screws  58  can be used to secured the spacer  20  to the frame portions  16 ,  18 . A blade receiving channel is defined between the first and second frame portions  16 ,  18  for receiving the blade in the closed position. The handle  12  can further include a forward spacer  56  secured between the frame portions  16 ,  18  adjacent the blade. The forward spacer  56  can also function as a blade stop that contacts the blade when it is folded closed to prevent further pivoting of the blade past the closed position. Although not shown in the drawings, the handle can also include scales and/or bolsters secured to the outer surfaces of the frame portions  16 ,  18 . Such scales and/or bolsters can be used for decorative or aesthetic reasons. 
         [0024]    The second frame portion  18  comprises a main body  24  and a biasing element in the form of, for example, a leaf spring  22  that can be integrally formed in the main body  24  of the second frame portion as depicted. In the context of the present application, the phrase “integrally formed” or “integrally connected” means that the leaf spring is machined, cut, or otherwise formed from the same piece of material that forms the main body without any fasteners or welds securing the leaf spring to the main body. In alternative embodiments, however, the biasing element (e.g., leaf spring  20 ) can be separately formed and subsequently connected to the main body  24  second frame portion, such as with mechanical fasteners or by welding the biasing element to the main body. 
         [0025]    As best shown in  FIG. 6 , the leaf spring  22  has a distal free end portion  26  and a proximal fixed end portion  28  that is integrally connected to the main body  24  of the second frame portion. Referring to  FIG. 1 , the blade  14  has a tang portion  30  that is pivotably connected to the free end portion  26  of the leaf spring, such as by a pivot element, or pivot pin,  32  that extends through a central opening  34  of the free end portion  26 , a washer  60 , and a corresponding opening in the blade tang  30 . A pivot screw  36  extends and is tightened into a threaded bore of the pivot pin  32  in a conventional manner. 
         [0026]    The leaf spring  22  functions to bias the blade  14  laterally toward the first frame portion  16  to lock the blade in the open and/or closed positions, as further described below. In alternative embodiments, the biasing element can take other forms, such as a coil spring or other resilient member interposed between the blade and the second frame portion. 
         [0027]    The second frame portion  18  can also include a spring clip  38  for clipping the knife to a pocket, belt, etc. The clip  38  can be integrally formed as shown or separately formed and subsequently attached to the second frame portion or at another location on the handle. As best shown in  FIG. 7 , the leaf spring  22  is bent to extend laterally outwardly from one side of the second frame portion and the spring clip  38  is bent to extend laterally outwardly from the opposite side of the second frame portion. 
         [0028]    The blade tang  30  in the illustrated embodiment includes a laterally extending main projection  40  and one or more laterally extending first locking elements in the form of locking pins, or projections,  42 . The first frame portion  16  is formed with a main opening  44  that is complementary to the projection  44  and one or more second locking elements in form of locking notches  46  in communication with the main opening  44  that are sized to receive the locking pins  42 . In the illustrated embodiment, as best shown in  FIG. 1 , the locking pins  42  are positioned on diametrically opposed sides of the main projection  40  and extend laterally from one side of the blade tang a distance less than the main projection. 
         [0029]    Desirably, the main projection  40  has a circular cross-sectional profile (perpendicular to the pivot axis of the blade) and the main opening  44  is circular to allow the main projection  40  to rotate within the main opening  44  when the blade is pivoted from the closed position to the open position, and vice versa. The main projection  40  desirably extends slightly beyond the outer side surface of the second frame portion  16  and has an exposed end surface  54  at the side of the handle that serves as a button or pressing surface for applying manual pressure against the blade when unlocking the knife. In the illustrated configuration, the main projection  40  is integrally formed as part of the blade tang. It should be noted, however, that the projection  40  can be separate component that is held in place against the side of the blade tang  30  by the pivot pin  32 . 
         [0030]    When the blade is in the closed position ( FIG. 8 ), the locking pins  42  are received in the notches  46 . The spring force of the leaf spring  22  forces the blade laterally against the first frame portion  16  (as indicated by arrow  48  in  FIG. 10 ), thereby retaining the locking pins  42  in the notches and preventing rotation of the blade relative to the handle. To open the blade, the user first applies a manual force against the main projection  40  in a direction laterally toward the second frame portion  18  (as indicated by arrow  50  in  FIG. 50 ) sufficient to overcome the force of the leaf spring and move the blade laterally a distance until the locking pins  42  are moved out of the notches  46 . 
         [0031]    While maintaining manual pressure laterally against the blade to keep the locking pins out of the notches, the blade can be pivoted to the open position by applying a rotational force to the blade in a conventional manner. To assist in rotating or “flipping” the blade open, the blade can include projections  52  (referred to as “flippers’). When the blade reaches the open position (which is about 180 degrees from the closed position in the illustrated embodiment), the locking pins  42  become aligned with the notches  46  and the leaf spring  22  forces the locking pins into the notches so as to lock the blade in the open position (referred to as the open and locked position). The blade can be pivoted closed in a similar manner by first moving the blade laterally to move the locking pins out of the corresponding notches and then rotating the blade until it reaches the closed position and the locking pins again become aligned with the notches, allowing the leaf spring to push the locking pins into the notches. 
         [0032]    In the illustrated embodiment, there are two locking pins  42  extending from the side of the blade and a corresponding number of locking notches. In other embodiments, the blade can have only one locking pin  42  or more than two locking pins spaced around the main projection  40 , and a corresponding number of locking notches. Also, the number of locking notches need not correspond to the number of locking pins. For example, the blade can have one locking pin  42  and the handle can have two locking notches, one of which is positioned to receive the locking pin when the blade is open and the other of which is positioned to receive the locking pin when the blade is closed. 
         [0033]    Moreover, in alternative embodiments, the positions of the locking pins  42  and the locking notches  46  can be reversed. In other words, the blade tang  30  can be formed with one or more locking notches and the first frame portion  16  can have one or more complimentary locking pins or projections that extend into the notches on the blade. 
         [0034]    In the illustrated embodiment, the blade is configured to pivot 180 degrees between the open and closed positions. Also, the locking pins  42  are spaced 180 degrees apart from each other, and so are the locking notches  46 . As such, the locking pins  42  can extend into and engage the locking notches  46  when the blade is in the closed position and the open position. However, it should be noted that the positions of the locking pins  42  and/or the locking notches  46  and/or the rotation of the blade can be modified to allow the locking pins  42  to engage the locking notches in the open position or the closed position but not both. 
         [0035]    For example, the locking pins  42  can be positioned so that they are aligned with the locking notches  46  when the blade is in the open position and the blade can be configured to pivot about 175 degrees. Thus, in this specific example, the locking pins  42  extend into the locking notches  46  when the blade is opened (and therefore lock the blade in the open position), but when the blade is pivoted closed, the locking pins  42  do not become aligned with the locking notches  46  since the blade does not rotate a full 180 degrees. As such, the locking pins  42  cannot engage the locking notches to lock the blade in the closed position. Instead, the locking pins  42  bear against the inner surface of the first frame portion  16  under the force of the leaf spring  22 . The force of the leaf spring  22  pressing the locking pins  42  against the inner surface of the first frame portion  16  desirably is sufficient to keep the blade from opening under its own weight. In this manner, the locking mechanism (including the locking pins and the locking notches) locks the blade in the open position and protects against inadvertent closing of the blade while the blade is being used, and when the blade is closed, the locking mechanism is effectively inactive or non-engaged so that the blade can be easily pivoted from the closed position without having to first manually disengage the locking mechanism. 
         [0036]    As noted above, referring to  FIG. 8 , the blade can include projections  52  to assist in opening the blade. The projections  52  desirably are non-parallel to each other and desirably are oriented at an angle of about 10 to 170 degrees relative to each other, with 90 degrees being a specific example. The projections  52  can be used to open the blade in several different ways. For example, the blade can be opened by applying a rotating force to the upper projection  52  in  FIG. 8  (usually with the index finger) while simultaneously flicking the wrist with sufficient force to completely open the blade. In another example, the blade can be opened by applying a rotating force to the lower projection  52  in  FIG. 8  with the thumb. Due to the position of the lower projection  52 , the blade can be pivoted through its full range using only the thumb. In another example, the blade can be opened using only the index finger (and without flicking the wrist) by first applying a rotating force to the upper projection  52  with the index finger to partially open the blade and then subsequently applying a rotating force to the lower projection  52  to further pivot the blade from the partially open position to the fully open position. 
         [0037]    If desired, an optional button, or extension,  82  ( FIG. 12 ) can be coupled the main projection  40  so as to extend laterally outwardly from the main opening  44  in the frame portion  16 . The button  82  is exposed at the side of the side of the handle and can be depressed by a user to move the blade laterally against the bias of the leaf spring when unlocking the blade. 
         [0038]      FIG. 13  illustrates an alternative frame portion  100  that can be used in lieu of frame portion  18 . In this embodiment, the entire distal end portion  102  of the frame portion  100  functions as the leaf spring and supports the blade in a pivotable manner, such as via a pivot pin that extends through an opening  104 . The frame portion  100  can be formed with an optional belt clip  106 . 
         [0039]    In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. I therefore claim as my invention all that comes within the scope and spirit of these claims.

Technology Classification (CPC): 1