Patent Publication Number: US-6701621-B2

Title: Releasable double locking knife

Description:
FIELD OF INVENTION 
     The present invention relates generally to knives, and more particularly to folding hand knives that are moved between a locked, open position and a folded position using one hand. 
     BACKGROUND OF THE INVENTION 
     It is known to provide knives that fold to a closed position and open to an in-use position using one hand. Such knives, however, are configured to operate using either only the left hand or only the right hand. A left handed knife, for example, is not operable using the right hand. Moreover, conventional, one-handed folding knives provide mechanisms for locking the knife in the extended position that are relatively easy to overcome, thereby compromising safety. 
     SUMMARY OF THE INVENTION 
     The present invention provides a releasable, double locking knife that may be operated using either the left hand or the right hand. The knife includes a body and a blade pivotally connected to the body for movement between a closed position and an open position. The body includes a pair of moveable arms that are biased toward one another into a locking position wherein the arms engage a stop surface of the blade, thereby locking the blade in the open position. Additionally, the blade carries a release mechanism that is operated by the user with the left or right thumb. When the knife is in the open position, the release mechanism is moveable toward the pair of moveable arms, and includes a pair of cam surfaces that urge the arms out of engagement with the blade, thereby permitting the blade to be folded into the closed position. 
    
    
     The features and advantages of the present invention described above, as well as additional features and advantages, will be readily apparent to those skilled in the art upon reference to the following description and the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a knife according to one embodiment of the present invention. 
     FIG. 2 is an exploded, perspective view of components of the knife shown in FIG.  1 . 
     FIG. 3 is a partially fragmented, perspective view of a release mechanism according to one embodiment of the present invention. 
     FIG. 4 is a side, elevational view of a knife according to the present invention in the open position with certain components removed for clarity. 
     FIG. 5 is a perspective view of the knife in FIG.  4 . 
     FIG. 6 is a partially fragmented, top, plan view of the knife in FIG.  1 . 
     FIG. 7 is a side, elevational view similar to FIG. 4, showing the blade of the knife moved slightly out of the open position. 
     FIG. 8 is a perspective view of the knife shown in FIG.  7 . 
     FIG. 9 is a top, plan view of the knife shown in FIG. 8 with all components shown. 
     FIG. 10 is a perspective view of a knife according to the present invention shown approximately half-way between the open and the closed positions with certain components removed for clarity. 
     FIG. 11 is a perspective view of a knife according to the present invention in the closed position with certain components removed for clarity. 
     FIG. 12 is a top, plan view of the knife according to the present invention in the closed position. 
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     The embodiments described below are merely exemplary and are not intended to limit the invention to the precise forms disclosed. Instead, the embodiments were selected for description to enable one of ordinary skill in the art to practice the invention. 
     Referring now to FIG. 1, a releasable, double locking knife according to one embodiment of the present invention is generally designated by number  10 . Knife  10  generally includes a body  12  and a blade  14 . Although this specification refers to blade  14  as a means for cutting material, it should be understood that the teachings of the present invention may be applied to a variety of different foldable tools, and is not limited to knives. For example, blade  14  may be replaced with a screw driver, a bottle opener, a cork screw, or any of a variety of other different types of tools. Body  12  generally includes a first side  16 , second side  18 , and a spacer  20  and may be formed in the shape of a handle having curved outlines as shown, or formed in any other shape for gripping when blade  14  is in the open position. 
     Referring now to FIG. 2, side  16  includes a scale  22  and a liner  24 . Scale  22  includes a recessed area  26 , and a pair of openings  28 ,  30  for receiving fasteners  32 ,  34  to connect side  16  to spacer  20 . Liner  24  may be shaped as shown to have an outline that corresponds substantially to the outline of scale  22 . Liner  24  includes a through hole  36  centered in a location adjacent one end of liner  24  that substantially corresponds to the center of recessed area  26  of scale  22  when liner  24  and scale  22  are connected together as will be further described below. Liner  24  further includes a pair of openings  38 ,  40  that similarly correspond to the locations of openings  28 ,  30  of scale  22  when liner  24  and scale  22  are connected together. 
     Liner  24  also includes a moveable arm, generally referred to by number  42 . In one embodiment of the invention, arm  42  is integral with and formed as a part of liner  24 . It should be understood, however, that arm  42  (and the opposed arm of side  18 ) may be separate from liner  24 , but connected or otherwise coupled to liner  24  to operate in the manner described below. In the illustrated embodiment, arm  42  includes a first end  44  and a second end  46 . Second end  46  depends from liner  24  while first end  44  (or free end of moveable arm  42 ) is moveable substantially into and out of a plane containing liner  24 . Thus, in this embodiment, arm  42  may be formed by cutting a slot  48  into liner  24  as shown in the drawings. As will be described in greater detail in the description of the operation of knife  10 , according to one embodiment of the present invention, arm  42  also includes an engagement surface  50  for cooperating with a portion of blade  14  to lock blade  14  in the open position, and a cam surface  51  for cooperating with a release mechanism of blade  14  to permit movement of blade  14  out of the open position. 
     As best shown in FIG. 1, arm  42  is bent or biased slightly downwardly (as viewed in the figure) relative to the plane containing liner  24 . Thus, free end  44  and engagement surface  50  are disposed, when in a relaxed or locking position, out of the plane containing liner  24  away from scale  22 . Liner  24  and arm  42  are formed, in one embodiment, of steel or other suitable material to provide strength and rigidity to body  12 , but permit some flexibility of arm  42  such that free end  44  may be moved into and out of its relaxed position. 
     Side  18  is essentially a mirror image of side  16 . Side  18 , generally includes a scale  52  and a liner  54 . Scale  52 , like scale  22 , includes a recessed area  56 , and a pair of openings  58 ,  60  for receiving fasteners  62 ,  64 . Liner  54 , like liner  24 , includes a through hole  66 , and a pair of openings  68 ,  70  that are substantially aligned with recessed area  56 , and openings  58 ,  60 , respectively, when liner  54  is attached to scale  52 . Liner  54  also includes a moveable arm  72  having a first end  74  (or free end) and a second end  76  that may depend from liner  54  in the manner described above with respect to arm  42 . In this embodiment, arm  72  is formed from the material forming liner  54  by providing a slot  78  as shown in the figure. Like arm  42 , arm  72  includes an engagement surface  80  and a cam surface  81 . Free end  74  of arm  72  is disposed, in its relaxed or locking position, out of a plane containing liner  54  and spaced apart from scale  52 . Accordingly, as will be further described below, when knife  10  is assembled, moveable arms  42 ,  72  are biased toward one another to lock blade  14  in the open position, but may be flexed apart from one another to release blade  14  from the open position. 
     Spacer  20  of body  12  has a thickness “A” that substantially corresponds to the width of a cavity  82  (FIG. 1) formed within body  12  for receiving blade  14  when in the closed position. Spacer  20  includes a first end  84 , a second end  86 , an inner side  88 , and an outer side  90 . First end  84  and outer side  90  are curved to substantially correspond to the shape of the outlines of scales  22 ,  52 , and liners  24 ,  54  such that when all of the components are connected together as shown in FIG. 1, they form a substantially smooth profile. Inner side  88  tapers toward side  90  with distance from end  84  as shown in the figure to provide space for blade  14  when folded into the closed position and received by cavity  82 . End  86  includes an abutment surface  92  that cooperates with a surface of blade  14  to limit the pivotal movement of blade  14  when blade  14  is moved to the open position as will be further described below. Finally, spacer  20  includes two threaded openings  94 ,  96  facing liner  24  and two threaded openings (not shown) facing liner  54 . Openings  94 ,  96  are located to align with openings  28 ,  30  of scale  22  and openings  38 ,  40  of liner  24 , respectively. Scale  22  and liner  24  are connected to spacer  20  by inserting fasteners  32 ,  34  through the appropriate openings in scale  22  and liner  24 , and threading fasteners  32 ,  34  into threaded openings  94 ,  96  of spacer  20 . The other threaded openings (not shown) of spacer  20  facing liner  54  are similarly located to receive fasteners  62 ,  64  when fasteners  62 ,  64  are inserted through the corresponding openings of scale  52  and liner  54  to connect scale  52  and liner  54  to spacer  20  in the manner described above. 
     Referring now to FIGS. 2 and 3, blade  14  generally includes a cutting portion  98  having a sharpened edge  100 , and a base generally referred to by the number  102 . Base  102  generally includes a first side surface  182 , a second side surface  184 , a recessed portion  104 , a wedge  108 , a thumb stud opening  110  (FIG.  1 ), a pivot opening  112 , and an abutment surface  114 . As shown, recessed portion  104  is recessed into both sides  182 ,  184  of base  102  to form a reduced thickness area, and includes a slot  116  for cooperating with a release mechanism  156  to release the knife  10  from its locked, open position. Wedge  108  includes a pair of stop surfaces  118 ,  120  for cooperating with engagement surfaces  80 ,  50  of arms  72 ,  42 , respectively, to lock blade  14  in the open position, as will be further described below. It should be noted that stop surfaces  118 ,  120  form a substantially obtuse angle relative to one another that substantially corresponds to an obtuse angle formed by engagement surfaces  80 ,  50  when arms  72 ,  42  are in the relaxed position and biased fully toward one another. Thumb stud opening  110  is situated adjacent edge  111  of base  102 , and includes a recess  122  into surface  182 , a through hole  124 , and a similar recess (not shown) into surface  184 . 
     Pivot opening  112  is sized to receive a pivot bearing  126  which is substantially cylindrical and has a height that is slightly greater than the thickness of base  102  of blade  14 . Pivot bearing  126  includes a central opening  128  that is sized to receive a pivot pin  130 . 
     Pivot pin  130  includes a shaft  132  that has a diameter that is slightly smaller than the diameter of opening  128  such that bearing  126  can pivot about shaft  132 . Pivot pin  130  also includes an enlarged diameter head  134 . Shaft  132  of pivot pin  130  is internally threaded to receive the threads  138  of a pivot screw  136  having a threaded shaft  139  and an enlarged diameter head  140  with a slot  142  for screwing pivot screw  136  into shaft  132  using a screwdriver or similar tool. As will be further described below, a pair of spacers  144 ,  146 , formed in the shape of thin washers having openings with a diameter that is larger than the outer diameter of pivot bearing  126 , are positioned within body  12  to stabilize blade  14  and minimize side-to-side motion of blade  14  during use. 
     As also shown in FIG. 2, knife  10  further includes a first thumb stud  148  and a second thumb stud  150 . First thumb stud  148  is substantially cylindrical in shape and has a threaded, internal opening (not shown). First thumb stud  148  has an outer diameter that substantially corresponds to the diameter of recess  122  such that first thumb stud  148  sits within recess  122 . Second thumb stud  150  includes a threaded shaft  152  and a stud portion  154  having a diameter that substantially corresponds to the diameter of another recess (not shown), similar to recess  122 , formed in surface  184  of base  102 . Thumb studs  148 ,  150  are attached to base  102  of blade  14  by inserting shaft  152  of second thumb stud  150  through thumb stub opening  110  and threading shaft  152  into the threaded, internal opening (not shown) of first thumb stud  148 . When shaft  152  of second thumb stud  150  is tightly threaded into the threaded, internal opening of first shaft  148 , first thumb stud  148  is tightly drawn into recess  122  and lateral movement of thumb studs  148 ,  150  is prevented by through hole  124  and recess  122 . 
     Finally, knife  10  further includes a release mechanism generally referred to by the number  156 . As best shown in FIG. 3, release mechanism  156  generally includes an actuator  158  and a rod  160 . Actuator  158  includes a body  162  with an end tab  164  having a stop surface  166 , a ridged bearing surface  168 , a pair of cam surfaces  170 ,  172  forming a wedge, and a pair of parallel tabs  174 ,  176 . Tab  174  includes an opening  178  that is aligned with a similar opening  180  formed in tab  176 . Release mechanism  156  is connected to base  102  of blade  14  by positioning actuator  158  such that parallel tabs  174 ,  176  fit within recessed portion  104 . The distance between the facing surfaces of parallel tabs  174 ,  176  is slightly greater than the thickness of recessed portion  104  of base  102 . Accordingly, tabs  174 ,  176  can move within recessed portion  104 . Actuator  158  is coupled to base  102  by inserting rod  160  through opening  178  of tab  174 , slot  116  of base  102 , and opening  180  of tab  176 . Rod  160  has an outer diameter that is slightly smaller than the width of slot  116  such that rod  160  is moveable along the length or axis of slot  116 . Rod  160  may be press fit into openings  178 ,  180  or otherwise connected to tabs  174 ,  176 . The path of travel of actuator  158  is substantially defined by slot  116  and the various surfaces of base  102  forming recessed portion  104 . As will be further described below, actuator  158  is thereby moveable toward and away from arms  42 ,  72  along the axis of slot  116 . 
     Referring back to FIG. 2, after release mechanism  156  and thumb studs  148 ,  150  are coupled to blade  14  in the manner described above, the overall assembly of knife  10  is accomplished by next inserting pivot bearing  126  into pivot opening  112  of base  102 . Pivot bearing  126  is press fit into opening  112  and because pivot bearing  126  is slightly longer than the thickness of base  102  at pivot opening  112 , the ends of pivot bearing  126  protrude slightly beyond side surfaces  182 ,  184  of base  102  as best shown in FIG.  3 . The length of pivot bearing  126  is the same as thickness “A” of spacer  20 . Spacer  144  is then placed on the protruding end of pivot bearing  126  and encircles pivot bearing  126 . The thickness of spacer  144  is such that its outer surface (relative to base  102 ) is flush with the end surface of pivot bearing  126  when spacer  144  is placed onto pivot bearing  126 . 
     Through hole  36  of liner  24  is then aligned with opening  128  of pivot bearing  126  and shaft  132  of pivot pin  130  is placed through through hole  36  and opening  128 . The partially assembled knife may then be flipped over while holding pivot pin  130  in place. Spacer  146  is then placed over the protruding end of pivot bearing  126  and through hole  66  of liner  54  is aligned with shaft  132  of pivot pin  130 . Threaded shaft  139  of pivot screw  136  is then inserted through through hole  66 , opening  128 , through hole  36 , and threaded into the threaded, internal opening (not shown) of shaft  132 . It should be understood by one skilled in the art that when pivot screw  136  is fully tightened into pivot pin  130 , blade  14  may rotate about a rotation axis (designated by the letter “B”) extending through pivot pin  130 , through hole  36 , spacer  144 , pivot bearing  126 , pivot opening  112 , spacer  146 , through hole  66  and pivot screw  136 . Moreover, the length of shaft  132  of pivot pin  130  is such that its free end is flush with the lower surface of liner  54  (as viewed in FIG. 2) so that when pivot screw  136  is fully threaded into shaft  132 , head  140  engages the free end of shaft  132 . This prevents pivot rod  130  and pivot screw  136  from impeding rotation of blade  14  by compressing liners  24 ,  54  against spacers  144 ,  146  and base  102  or against pivot bearing  126 . While blade  14  is not compressed between liners  24 ,  54 , the length of shaft  132  of pivot pin  130  and the thickness of base  102 , pivot bearing  126 , and spacers  144 ,  146  are such that blade  14  is prevented from wobbling side-to-side relative to liners  24 ,  54 . 
     Spacer  20  may then be positioned between liners  24 ,  54  such that the threaded openings  94 ,  96  align with openings  38 ,  40  of liner  24 . Scale  22  may then be placed onto liner  24  such that head  134  of pivot pin  130  is received within recessed area  26  and openings  28 ,  30  align with openings  38 ,  40  of liner  24 , respectively. Fasteners  32 ,  34  are used to connect scale  22  to liner  24  and spacer  20  as described above. It should be understood that more than two fasteners (and corresponding openings) may be provided, or a single fastener may be used to attach the above-described components together. Also, one or more such fasteners may extend from one of scales  22 ,  51 , through spacer  20 , and connect to the other of scales  22 ,  52 . 
     The threaded openings (not shown) on the other side of spacer  20  are also aligned with openings  68 ,  70  of liner  54 . Scale  52  may then be placed on liner  54  such that head  140  of pivot screw  136  is received in recessed area  56 , and openings  58 ,  60  are aligned with openings  68 ,  70  of liner  54 . Fasteners  62 ,  64  are used to connect scale  52  to liner  54  and spacer  20  in the manner described above. 
     FIGS. 4-6 show knife  10  locked in an open position. For clarity, scale  22 , liner  24 , pivot rod  130 , and spacer  144  are not shown in FIGS. 4 and 5. When blade  14  is in the open position, moveable arms  42 ,  72  extend into cavity  82  (FIG. 6) such that free ends  44 ,  74  are in their substantially relaxed position. As best shown in FIG. 5 and 6, when in this position, engagement surfaces  50 ,  80  of free ends  44 ,  74 , contact stop surfaces  120 ,  118  of wedge  108 , respectively. As best shown in FIG. 5, blade  14  is thereby locked in the open position and prevented from pivoting counter-clockwise (as viewed in the figures). It should be noted that further clockwise rotation of blade  14  is also prevented by engagement between abutment surface  92  of spacer  20  and abutment surface  114  of base  102 . When in this open, in-use position, blade  14  is securely locked by both inwardly biased moveable arms  42 ,  72 , thereby preventing accidental closure of blade  14  into body  12 . 
     As is also shown in FIGS. 4 and 5, when blade  14  is in the open position, actuator  158  of release mechanism  156  is positioned away from arms  42 ,  72 . More specifically, rod  160  is positioned within slot  116  adjacent the end of slot  116  opposite wedge  108 . 
     Blade  14  may be moved out of the locked, open position by first moving release mechanism  156  toward arms  42 ,  72  as shown in FIGS. 7-9. More specifically, pressure is applied to bearing surface  168  of actuator  158  to move actuator  158  toward arms  42 ,  72  through the path of travel defined by slot  116 . As actuator  158  is moved through its path of travel, rod.  160  slides through slot  116  toward the end of slot  116  adjacent wedge  108 . As best shown in FIGS. 8 and 9, as actuator  158  is moved toward arms  42 ,  72 , cam surfaces  170 ,  172  bear against cam surfaces  51 ,  81  of free ends  44 ,  74 . As actuator  158  is further moved in this direction, cam surfaces  170 ,  172  wedge between and spread apart free ends  44 ,  74  against the inward biasing force of arms  42 ,  72 . When actuator  158  reaches the end of its path of travel, free ends  44 ,  74  are substantially flexed out of their relaxed position by an amount sufficient to permit wedge  108  (and the remainder of base  102 ) to slide between arms  42 ,  72 . As best shown in FIG. 9, when fully urged away from one another by actuator  158 , free ends  44 ,  74  are substantially planar with liners  24 ,  74 , respectively, and are separated by a distance that is substantially equal to the thickness of base  102  of blade  14 . Since free ends  44 ,  74  are no longer in locking engagement with stop surfaces  120 ,  118 , blade  14  may be pivoted counter-clockwise (as viewed in the figures) out of the open position by applying pressure to edge  111  of blade  14 . 
     FIG. 10 shows blade  14  approximately half-way through its rotation about rotation axis “B” between the open position and the closed position. As blade  14  rotates, end  44 ,  74  of arms  42 , 72  are urged against and ride along side surfaces  182 ,  184 , respectively, of blade base  102 . Since arms  42 ,  72  are flexed out of their relaxed position, the biasing force generated by the resiliency of arms  42 ,  72  urges the arms against side surfaces  182 ,  184 , thereby providing some resistance to the rotation of blade  14 . 
     FIGS. 11 and 12 show knife  10  in its closed position. As best shown in FIG. 11, a substantial portion of blade  14 , including sharpened edge  100  is disposed within cavity  82 . When blade  14  reaches the closed position, stop surface  166  of end tab  164  engages side  88  of spacer  20  at end  86 . This engagement prevents further rotation of blade  14  about axis “B,” and prevents sharpened edge  100  of blade  14  from engaging side  88  of spacer  20 . As shown in FIG. 12, free ends  44 ,  74  of arms  42 ,  72  remain biased against side surfaces  182 ,  184 , respectively. The compressive force supplied by ends  44 ,  74  retains blade  14  in the closed position. This compressive force, however, can be overcome by pushing against either thumb stud  148  or thumb stud  150 . 
     While holding body  12  with the palm and fingers, of one hand, the thumb of that hand is free to urge the appropriate thumb stud  148 ,  150  upwardly causing rotation of blade  14  out of the closed position. In this manner, blade  14  may be rotated clockwise (as viewed in the figures) to the open position as shown in FIG.  1 . When blade  14  reaches the open position, ends  44 ,  74  of arms  42 ,  72 , snap inwardly toward one another to engage stop surfaces  120 ,  118 , respectively, thereby locking blade  14  in the open position as described above. 
     The foregoing description of the invention is illustrative only, and is not intended to limit the scope of the invention to the precise terms set forth. Although the invention has been described in detail with reference to certain illustrative embodiments, variations and modifications exist within the scope and spirit of the invention as described and defined in the following claims.