Patent Publication Number: US-6338431-B1

Title: Locking knife blade with moving locking mechanism on blade

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from U.S. Provisional Patent Application Ser. No. 60/130,401, filed Apr. 19, 1999. 
    
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates generally to a folding knife, and particularly to a folding knife having a locking mechanism that locks the blade in an open, deployed position and that may be used to both open and close the blade. This allows simple, one-handed unlocking and closing of the blade, with a single thumb-actuated motion. The same locking mechanism may be used for one-handed opening of the blade. In an alternative embodiment, the invention includes a spring mechanism and blade configuration that make opening the knife even easier. 
     Examples of folding knives may be found in the following U.S. patents: U.S. Pat. No. 1,454,665, issued May 8, 1923; U.S. Pat. No. 1,743,022, issued Jan. 7, 1930; U.S. Pat. No. 4,040,081, issued Aug. 9, 1977; U.S. Pat. No. 4,404,748, issued Sep. 20, 1983; U.S. Pat. No. 4,451,982, issued Jun. 5, 1984; U.S. Pat. No. 4,502,221, issued Mar. 5, 1985; U.S. Pat. No. 4,719,700, issued Jan. 19, 1988; U.S. Pat. No. 4,805,303, issued Feb. 21, 1989; U.S. Pat. No. 4,811,486, issued Mar. 14, 1989; U.S. Pat. No. 4,837,932, issued Jun. 13, 1989; U.S. Pat. No. 4,974,323, issued Dec. 4, 1990; U.S. Pat. No. 4,979,301, issued Dec. 25, 1990; U.S. Pat. No. 5,044,079, issued Sep. 3, 1991; U.S. Pat. No. 5,060,379, issued Oct. 29, 1991; U.S. Pat. No. 5,095,624, issued Mar. 17, 1992; U.S. Pat. No. 5,111,581, issued May 12, 1992; U.S. Pat. No. 5,293,690, issued Mar. 15, 1994; U.S. Pat. No. 5,331,741, issued Jul. 26, 1994; U.S. Pat. No. 5,502,895, issued Apr. 2, 1996; U.S. Pat. No. 5,515,610, issued May 14, 1996; U.S. Pat. No. 5,537,750, issued Jul. 23, 1996; U.S. Pat. No. 5,689,885, issued Nov. 25, 1997; U.S. Pat. No. 5,692,304, issued Dec. 2, 1997; U.S. Pat. No. 5,737,841, issued Apr. 14, 1998; U.S. Pat. No. 5,755,035, issued May 26, 1998; U.S. Pat. No. 5,802,722, issued Sep. 8, 1998; U.S. Pat. No. 5,822,866, issued Oct. 20, 1998; U.S. Pat. No. 5,826,340, issued Oct. 27, 1998; and U.S. Pat. No. 5,887,347, issued Mar. 30, 1999, the disclosures of which are incorporated herein by this reference thereto. 
     Common elements to folding knives include a handle and a blade pivotally connected to an end of the handle so that the blade pivots with respect to the handle between an open position in which the blade is extended away from the handle and a closed position in which the blade is at least partially received within the handle. In one embodiment of the present invention, a locking mechanism is formed from a post slidably mounted on the blade to engage the end of the handle to lock the blade in the open position. The post and blade are adapted to allow simple, one-handed unlocking and closing of the blade, with a single thumb-actuated motion. The post is also adapted to allow one-handed opening of the blade. 
     In other embodiments, which may or may not include the locking mechanism discussed above, an opening is defined through the handle so that an oversized tang portion of the blade may extend through the opening when the blade is in the closed position. An actuating spring may also be provided to operatively connect the blade and handle, such that the actuating spring urges the blade into the open position once the blade is rotated open beyond an equilibrium point. The actuating spring and oversized tang portion may be configured so that pushing the oversized tang portion into the handle causes the blade to pivot open beyond the equilibrium point so that the actuating spring causes the blade to pivot the rest of the way open. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric view of a folding knife according to the present invention. 
     FIG. 2 is a front plan view of the knife of FIG. 1, showing the knife blade stored within a blade-receiving channel. 
     FIG. 3 is a side view of a folding knife according to the present invention, showing an alternate configuration for the knife blade. 
     FIG. 4 is an isometric view showing a user&#39;s hand opening the blade of the knife of FIG.  1 . 
     FIG. 5 is an isometric view showing a user&#39;s hand unlocking and closing the blade of the knife of FIG.  1 . 
     FIG. 6 is an expanded, fragmentary side view showing the connection between the locking mechanism and blade of the knife of FIG.  1 . 
     FIG. 7 is an expanded, fragmentary side view similar to FIG. 6, but showing an alternate means of connecting the locking mechanism and blade. 
     FIG. 8 is a side view of a knife blade and a grip and spring assembly according to the present invention, the assembly including an actuating spring for operatively interconnecting the blade and handle of the knife. 
     FIG. 9 is an exploded isometric view of the knife of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1 and 2 depict an embodiment of a folding knife  10  constructed according to the present invention. The depicted knife has an elongate blade  12  with a tang  12   a  pivotally connected to an end  16   a  of handle  16  so that the blade pivots with respect to the handle about a pivot axis P between an open position O and a closed position C. In the open position, the blade is extended away from the handle so that it is deployed and ready for use. From the open position, the blade can be folded toward the handle into the closed position, in which the blade is partially received for storage within a blade-receiving channel  18  defined in the handle. 
     The folding knife may be provided with a locking mechanism movably secured to the blade that locks the blade in the open, deployed position, and that may be used to both open and close the blade. When the blade is open, the locking mechanism may be moved into a locking position where the locking mechanism interacts with the knife handle to lock the blade in the open position. From this locked state, the locking mechanism can be retracted to unlock the blade so that it may be freely pivoted to the closed position. Further, the locking mechanism may be positioned on the blade so that a simple, one-handed motion may be used to open and lock the blade, and to unlock and close the blade. 
     As depicted in FIG. 1, the locking mechanism may be provided as a post  30 , which extends transversely from flat surface  12   b  of blade  12 . Post  30  is positioned near blade tang  12   a  but spaced from pivot axis P so that the post is exposed during the rotation of blade  12  between the closed and open positions. Post  30  is slidably held in a slot (shown in FIGS. 6 and 7) defined through blade  12  so that the post slides along the surface of the blade. Post  30  is slidable between a retracted position R at one end of the slot and a locking position L at the other end of slot, the locking position being spaced further from blade point  12   c  than the retracted position. As will be described in detail with reference to FIGS. 6 and 7, a spring may be provided in the slot to urge post  30  toward the locking position. Coverplates  32  are fixed to post  30  to conceal the slot and maintain the spring within the slot. Coverplates  32  may be formed integrally with post  30 , as shown in FIG. 1, or formed separately and then secured to the post. 
     Post  30  and handle end  16   a  interact to lock the blade in the open position. Specifically, handle end  16   a  is adapted so that, when the blade is rotated into open position O, post  30  is allowed to slide into locking position L. When post  30  is in locking position L, handle end  16   a  blocks the post to prevent blade  12  from being pivoted toward closed position C, as shown in FIG.  1 . In addition to the locking capability, post  30  can be used by an operator of the knife to easily open and close the blade, as will be later explained. 
     FIG. 3 depicts a folding knife having the same locking mechanism, post  30 , but with an alternately configured blade  40 . FIG. 3 shows the interaction of post  30  with handle end  16   a  as the blade is pivoted with respect to the handle, including the locking of the blade in open position O. Handle end  16   a  may be formed to have an exposed exterior edge surface  16   b  including a rounded cam portion  16   c  and a locking portion  16   d.  Cam portion  16   c  and locking portion  16   d  are separated by corner  16   e.  Typically, and as depicted, locking portion  16   d  is formed as a notch cut into a back portion of the handle end  16   a.  A spring (not shown) may be provided to urge post  30  toward the locking position, and thus into engagement with handle end  16   a.  As blade  40  is rotated in a clockwise direction from the closed position toward the open position, post  30  thus first engages rounded cam portion  16   c.  With further rotation of blade  40 , post  30  passes around corner  16   e  and into the notch to engage locking portion  16   d  of handle end  16   a.  While post  30  is maintained in locking position L, locking portion  16   d  of handle end  16   a  blocks the post and thus prevents blade  40  from being pivoted toward closed position C. 
     To unlock blade  40 , post  30  is pushed toward retracted position R to disengage the post from locking portion  16   d  of handle end  16   a.  Once post  30  and locking portion  16   d  are thus disengaged, handle end  16   a  no longer blocks the post, and blade  40  may be pivoted toward the closed position. Although the depicted knife has a notch formed in the handle, handle end  16   a  can be formed in a variety of ways to interact with post  30  to selectively lock blade  40  in the open, deployed position. 
     As previously noted, FIG. 3 will also be seen to depict a blade having an alternate configuration from that shown in FIGS. 1 and 2. Specifically, blade  40  has an oversized tang portion  40   a  that is dimensioned to extend through the handle&#39;s blade receiving channel and out an opening in handle back  16   f  when the blade is closed. When thus exposed out the back opening, oversized tang portion  40   a  can be pushed back into the handle to pivot blade  40  toward the open position. 
     The folding knife of FIG. 3 may further be provided with an actuating spring  72 , to be described in more detail with respect to FIG. 8, that operatively interconnects blade  40  and handle  16 . Handle  16  and blade  40  cause the actuating spring  72  to be compressed as they pivot relative to one another, such that the actuating spring exerts a closing or opening force on blade  40 , depending on the relative position of the blade and handle. When blade  40  is at equilibrium position E, the actuating spring is maximally compressed, and when the blade is in either the open or closed positions, the spring is relatively uncompressed. Accordingly, when blade  40  is positioned rotationally to either side of equilibrium position E, the actuating spring  72  causes the blade to pivot away from the equilibrium position. Thus, when blade  40  is between equilibrium position E and the closed position, the actuating spring urges the blade into the closed position. Similarly, when the blade is rotationally between the equilibrium position and the open position, the spring urges the blade toward the open position. 
     Oversized tang portion  40   a  and the actuating spring  72  may be adapted so that the blade may quickly and easily be rotated into the open position. Specifically, and as shown in FIG. 3, oversized tang portion  40   a  may be sized so that fully pushing the oversized tang portion  40   a  into the opening in handle back  16   f  causes blade  40  to pivot open beyond equilibrium position E. At that point, the actuating spring  72  exerts an opening force to pivot blade  40  the rest of the way open. This allows the depicted knife to be opened in a variety of ways. For example, a person can use their thumb or fingers to push oversized tang portion  40   a  into the opening in handle back  16   f  and thus open blade  40 . Alternatively, the knife can swiftly be brought into contact with a person&#39;s thigh or some other object to force oversized tang portion  40   a  into the opening. 
     Although a sliding post locking mechanism is depicted in FIG. 3, embodiments of the invented folding knife having an oversized tang portion may or may not be provided with this type of locking mechanism. Instead, the handle of the folding knife may be provided with a movable liner that can be positioned to abut the blade tang to thereby lock the blade in the open position. To unlock the blade, the liner is pushed in a sideways direction until it no longer blocks rotation of the blade. The liner may be biased so that it moves into the locking position to lock the blade whenever the blade is pivoted to the open position. Furthermore, any other suitable locking mechanism may be used, or the embodiment may not have a locking mechanism at all. 
     FIG. 4 depicts the folding knife of FIGS. 1 and 2 being opened by a user&#39;s hand. As will be appreciated from this and the preceding figures, post  30  is typically positioned on blade  12  so that it is exposed for manipulation by a user throughout the entire range of the blade&#39;s pivotal travel. Because post  30  extends transversely from the blade and is spaced from pivot axis P, an external force parallel to the plane of the blade may be exerted upon the post to cause the blade to pivot with respect to the handle. 
     As seen in FIG. 4, thumb  50  exerts opening force F o  on post  30  to cause blade  12  to pivot toward the open position. As indicated, the position of the post  30  allows the blade to be easily opened with one hand, with a simple thumb-actuated motion. In addition, the depicted knife may be provided with an actuating spring  72  operatively connecting the handle and blade, as described with reference to FIG. 3, to further facilitate opening of the blade. 
     As shown in FIG. 5, a similar motion may be used to unlock blade  12  and rotate the blade from the open position into the closed position. Thumb  50  is shown to exert a closing/unlocking force F c  upon post  30  to disengage the post from the locking portion  16   d  of handle end  16   a  and rotate the blade toward the closed position. 
     FIGS. 6 and 7 are enlarged fragmentary views of the knife of FIGS. 1 and 2 that depict a slot  60  formed through blade  12  for slidably holding locking post  30 . A central portion  30   a  of post  30  is transversely positioned within slot  60 , which is elongate and larger in width than the diameter of central portion  30   a  of post  30 . Spring  62  is positioned in slot  60  and secured between blade  12  and central portion  30   a  of post  30  to urge the post along the slot  60  toward slot end  60   a  into the locking position. A first end  62   a  of spring  62  is attached to the post&#39;s central portion  30   a  with a second end  62   b  being attached to blade  12  near slot end  60   b.    
     As shown in FIG. 6, slot  60  may be provided with a spring attachment member  64  that extends into slot end  60   b,  with spring end  62   b  being wrapped around attachment member  64 . Though depicted as a small, cylindrical post, attachment member  64  can be of any size and shape suitable for attachment with spring  62 . Alternatively, as shown in FIG. 7, a recessed area  66  may be provided at slot end  60   b,  with a hole  66   a  being defined through the recessed area  66  so that spring end  62   b  can be threaded through the hole to secure the spring to the blade. 
     FIG. 8 depicts a grip and spring assembly  70  constructed according to the present invention, with a blade  12  pivotally attached to the grip and spring assembly  70 . A fully assembled folding knife would include an additional grip piece fastened to grip and spring assembly  70  to pivotally secure the blade between the grip and spring assembly and the additional grip piece. The depicted knife is partially assembled to clearly show the operation of actuating spring  72 . 
     Grip and spring assembly  70  includes a grip piece  74 , a reinforcement member  76  secured to an end of the grip piece  74 , a coverplate  78  fastened to an interior side of the grip piece  74 , and an actuating spring  72 . The way in which grip piece  74 , reinforcement member  76 , and coverplate  78  are configured will be more clearly depicted and explained with reference to FIG.  9 . Actuating spring  72  is contained within a cavity formed between coverplate  78  and grip piece  74 . A first end  72   a  of actuating spring  72  extends out of the cavity through an arcuate notch  80  formed by the edges of reinforcement member  76  and coverplate  78 , and is attached to blade  12 . Spring end  72   a  is attached to blade  12  at a location spaced from the blade&#39;s pivot point, such that the spring travels along an arcuate path as the blade is rotated. Arcuate notch  80  is adapted to accommodate the travel of spring end  72   a.  A second end  72   b  of the actuating spring is movably held within a slot  82  formed by the coverplate  78  and handle piece. 
     Spring  72  is subjected to varying degrees of compression as blade  12  is pivoted. When blade  12  is in the open position, the spring is in an uncompressed state. As blade  12  is rotated toward the closed position, spring end  72   a  follows the indicated arcuate path and spring end  72   b  is forced into contact with slot end  82   a,  causing spring  72  to be compressed. Spring  72  is maximally compressed when spring end  72   a  is at the point of its arcuate travel where it is closest to slot end  82   a.  As previously discussed, this occurs when blade  12  is in equilibrium position E, shown here in dashed lines. When blade  12  is positioned to either side of equilibrium point E, spring  72  forces the blade toward the open or closed position, in which the spring is in a relatively uncompressed state. 
     FIG. 9 is an exploded isometric view of the folding knife depicted in FIGS. 1 and 2 showing how handle grip pieces  74  and  90 , blade  12 , post  30 , and actuating spring  72  are assembled with the various other parts of the knife. As indicated, coverplate  78  and reinforcement member  76  are fastened to grip piece  74  with screws  92 , so that spring  72  is secured within a cavity formed by coverplate  78  and grip piece  74 . Interior surface  74   a  of grip piece  74  is formed to have a two-depth recess  74   b  including shelf portions  74   c  and a deeper central portion  74   d.  Coverplate  78  is fastened to shelf portions  74   c  so that the coverplate can be fastened flush to interior surface  74   a  of grip piece  74  while still providing a cavity in which spring  72  is able to move. 
     Grip piece  74 , spring  72 , coverplate  78 , and reinforcement member  76  comprise a grip and spring assembly that may be assembled separately from the other depicted components. In some settings, stage assembly is simpler and less expensive than known methods of manufacture, which often require that all parts of the knife be simultaneously aligned and fastened together. 
     The depicted knife includes a second reinforcement member  94  fastened to grip piece  90  with screws  96 . Reinforcement members  76  and  94  strengthen the end of handle  16  and partly form the exterior edge surface engaged by post  30  as the blade pivots between the open and closed positions. As indicated, locking post  30  may be formed of two complementary lock post pieces  98  having integrally formed spring-retaining coverplates  100 . The lock post pieces are secured together by a fastener  102  that extends through slot  60  formed through blade  12 . The lock post pieces are slidable along the length of slot  60  and, as previously described, a spring  62  is provided to bias post  30  along the slot so that the post engages the end of the knife handle. 
     The blade is pivotally secured between grip pieces  74  and  90  and reinforcement members  76  and  94  with an internally threaded pivot post  110  that extends through holes in the grip pieces, reinforcement members and blade to receive a fastener  112 . The grip pieces are secured together with fasteners  114 . Finally, a stop post  116  is secured between reinforcement members  76  and  94  to abut the blade tang when the blade is in the open position and provide a terminal point beyond which the blade cannot be opened. 
     While the invention has been disclosed in its preferred form, the specific embodiments thereof as disclosed and illustrated herein are not to be considered in a limiting sense as numerous variations are possible. The subject matter of the invention includes all novel and non-obvious combinations and subcombinations of the various features, elements, functions and/or properties disclosed herein. No single feature, function, element or property of the disclosed embodiments is essential. The following claims defined certain combinations and subcombinations which are regarded as novel and non-obvious. Other combinations and subcombinations of features, functions, elements and/or properties may be claimed through amendment of the present claims or presentation of new claims in this or a related application. Such claims, whether they are different, broader, narrower or equal in scope to the original claims, are also regarded as included within the subject matter of the invention.