Folding Knife

A number of folding knife configurations have been used in the past. FIG. 1 depicts a knife generally of the type described in U.S. Pat. No. 3,942,249 issued Mar. 9, 1976 to Mr. Paul W. Poehlmann. In this device, a handle is formed by left and right side plates, 1007, 1008 sandwiching a spacer 1009 and held together by rivets 1011 and 1012. A blade 1041 is coupled to the handle so as to be rotatable about axis 1018 from the extended configuration depicted in FIG. 1 to a folded configuration with the blade 1041 adjacent the spacer 1009 and substantially between the sideplates 1007 and 1008. A key locking mechanism made up of hub 1021, spring 1056, detent 1048 and nut 1036 resides in openings 1016, 1043, 1029 in the left plate 1007, blade 1041 and right plate 1008 respectively. Keys 1052, 1053 interact with keyways 1044, 1046, 1038, 1039 in the blade 1041 and right plate 1008 respectively. In the normal configuration, the key locking mechanism is configured so that the keys 1052, 1053 reside partially in the blade keyways 1044, 1046 partially in the plate keyways, 1038, 1039. Thus locking the blades 1041 in a position with respect to the handle. When the user pushes on the activation surface of the key locking mechanism, (e.g. depressing right surface of the detent 1048) the keys 1052, 1053 are moved, against the urging of spring 1056 so as to reside solely within the blade keyways 1044, 1046 and to be clear of the plate keyways 1038 and 1039. With the activation surface so depressed, the key locking mechanism can be rotated, carrying the blade 1041 with it and rotating the blade 1041, e.g., from the extended configuration to the folded configuration or vice-versa. After such rotation, once the detents 1053, 1052 are aligned with the plate keyways 1038, 1039 the spring 1056 will urge the key device back into the relaxed configuration such that the keys 1053 1052 reside partially in the blade keyways 1044 1046 and partially in the plate keyways 1038, 1039 thus locking the blade in the folded configuration.

Although the configuration shown in FIG. 1 has proved to be useful and desirable for a multitude of purposes, it can be difficult and/or expensive to produce the device with sufficient accuracy e.g. to achieve a desired degree of locking of the blade with no play. In most cases, using normal manufacturing tolerances, a knife which is configured with tolerances to permit the detents 1052, 1053 to slide easily in the keyways 1044, 1046, 1038, 1039 may often result in a locked configuration which has an undesirable amount of play, i.e., in which the blade 1041 can rotate a small amount with respect to the handle, even in the locked position. Furthermore, the configuration depicted in FIG. 1 is such that the blade in the extended position is exactly 180.degree. rotationally displaced from the blade in the closed or folded configuration, which places undesirable constraints on the knife design and restricts the perimeter design of the blade. In knives which provide for the meeting of stop surfaces, some geometries caused undesirable movement of forces on components, upon such meeting, because of a resultant camming action of the respective parts. Furthermore, in the embodiment of FIG. 1, there may be an undesirable amount of blade play in the extended position.

Accordingly, it would be useful to provide a folding knife which provides for secure locking in the extended and folded configuration with minimum play, which permits locking after a rotational blade displacement of other than 180.degree., preferably less than 180.degree. and/or which has improved ease or economy of design, manufacture, repair and/or maintenance.

According to the present invention, the blade is held in a locked configuration by the combination of the interaction of a key and keyway and the abutment of a stop surface coupled to or formed in the handle with a corresponding surface coupled to or formed in the blade. Preferably at least one of the stop surfaces is adjustable, e.g. via a set-screw mechanism. In one embodiment, the interaction of a key and keyway act to lock the blade against rotation in a first rotational direction while the interaction of the stop surfaces act to lock the blade against rotation in the opposite rotational direction. Preferably the extended position of the blade is rotationally displaced from the folded position of the blade by an angle which is different from and preferably less than, 180.degree. such as by providing keyway contact surfaces or key contact surfaces which are non-parallel with each other. In one embodiment, more than two key surfaces contact corresponding keyway surfaces when the blade is in the locked configuration.

FIG. 1 is an exploded perspective view of a folding knife of previous configuration;

FIG. 2 is an exploded perspective view of a knife according to one embodiment of the present invention;

FIG. 3 is a schematic right side elevational view of a knife according to one embodiment of the present invention with the blade in a folded configuration;

FIG. 4 is a right side elevational view of the knife of FIG. 3 with the blade in the extended configuration;

FIG. 5 is a partial right side elevational view, partially cut away, of the knife FIG. 4 with the nut removed;

FIG. 6A is a left side elevational view of a knife according to an embodiment of the present invention with the blade in a folded configuration, and showing the extended blade in the phantom with indications in the phantom of a manner of holding and folding and unfolding the blade;

FIG. 6B is a cross-sectional view taken along line 6b--6b of FIG. 4;

FIG. 7 is a partial side elevational view of the knife of FIG. 5 with the right side blade removed;

FIG. 8 is a cross-sectional view corresponding to the view of FIG. 6B but with the key device depressed;

FIG. 9 is a right side elevational view corresponding to the view of FIG. 5 but with the blade in the folded configuration;

FIG. 10 is a right side elevational view of a knife corresponding to the view of FIG. 9 but with the right side plate removed;

FIG. 11 is a right side elevational view of a knife according to an embodiment of the present invention with the blade extended, partially cut away and with the nut removed;

FIG. 12 is a right side elevational view of the knife depicted in FIG. 11 but with the blade in the folded configuration;

FIG. 13 is a perspective view of a key device according to one embodiment of the present invention;

FIG. 14 is a right side elevational view of a knife according to an embodiment of the present invention,. partially cut away, with the nut removed, using the key of FIG. 13;

FIG. 15 is a left side elevational view of a knife according to one embodiment of the present invention.

As depicted in FIG. 2, in one embodiment a handle formed of right plate 1, left plate 7 and spacer 3 is held together by fastening devices such as rivets 202, 204. A blade 2 is mounted to the handle so as to permit rotation about axis 206 from the folded configuration depicted in FIG. 3 to the extended configuration depicted in FIG. 4. The axis 206 is defined by a key locking mechanism including a carrier 5, a spring 208, key device 6 and nut 4. Openings and keyways 210, 212, 244 in the left plate 7, blade 2 and right plate 1 respectively define a space for accommodating the key locking mechanism.

In the embodiment of FIG. 2, first and second keyways 214, 216 are formed in the surface of opening 212 defining blade keyway contact surfaces 218a, 218b, 218c, 218d which, during operation and/or locking, contact corresponding key contact surfaces 220a (not shown) 220b, 220c, 220d as described below. In the depicted embodiment, blade keyway contact surfaces 218a, 218d lie along a first plane 222a and blade keyway contact surfaces 218b, 218c lie along a second plane 222b substantially parallel with the first plane 222a. In the embodiment of FIG. 2, the axis defined by the keys is substantially parallel to the longitudinal axis of the knife, so that blade play that may arise from e.g. key-keyway clearances will be substantially along the longitudinal knife axis, which is preferable to blade play along a perpendicular axis of the type that may arise in the configuration shown in FIG. 1.

Right plate opening 244 also defines keyways having keyway contact surfaces 22a, 22b, 23a, 23b. In the depicted embodiment, contact surfaces 23a, 23b lie on planes 224a, 224b and right plate keyway contact surfaces 22a, 22b lie along planes 226a, 226b. In the depicted embodiment, right plate keyway contact surface 22a is not parallel with surface 23a, but, rather, lies in a plane 226a which is at a first angle 228a with respect to plane 224b. Similarly, right plate keyway contact surface 22b lies in a plane 226b which is at an angle 228b with respect to plane 224a. This configuration can be seen in FIG. 5. In the depicted embodiment angles 228a and 228b are substantially the same. The value of the angles 228a, and 228b will affect, among other things, the amount of angular rotation of the blade between the embodiment of FIG. 3 (folded configuration) and FIG. 4 (extended configuration). In one embodiment, angles 228a, 228b are less than about 15.degree., to provide for blade travel from the open to the closed configuration through an angle between about 165 degrees and about 180 degrees.

Returning to FIG. 2, a first stop device 9 coupled to the handle, and specifically to the spacer 3 interacts with a stop surface 15 of the blade to partially define an open or extended configuration of the blade as described below. A second stop device 8 interacts with a second blade stop surface 232 to partially define a blade position for the closed configuration depicted in FIG. 3. Preferably the set device 9 is adjustable to that the location of the contact surface 9a of stop device 9 can be moved or adjusted. In one embodiment, stop device 9 is a set screw which can be rotated in a screw-like fashion to adjust its contact surface 9a so as to bear against blade stop surface 15 when the blade 2 is in the desired extended position. Similarly, stop device 8 is preferably adjustable, e.g. by being a set screw such that its contact surface 8a can be adjusted to a location such that is bears against blade stop surface 232 when the knife is in the folded configuration shown in FIG. 3, as described more fully below. Preferably, the contact surfaces of the stop devices 8 and 9 are perpendicular to the respective contact faces 15 and 232. Although other, non-perpendicular configuration would be at least partially operable, it is believed that the perpendicular configuration provides the most positive and lasting adjustment.

When the key locking mechanism is in the relaxed configuration the spring 208, partially compressed between the carrier 5 and the key 6, positions the key along axis 206 in a location such that the first and second key devices 234, 236 are positioned partially in the keyways 238, 240 of the right plate 1 and partially in the keyways 214, 216 of the blade 2

As shown on FIG. 5, when the knife is in the open configuration, key contact surface 220a contacts keyway surface 23a and key contact surface 220c contacts right plate keyway contact surface 23b. The abutment of contact surfaces 220a with 23a and 220c with 23b thus prevents the key 6 from rotating clockwise 239 with respect to the right plate 1. The view of FIG. 7 (corresponding to the view of FIG. 5 but with the right plate 1 removed) shows that the key devices 234, 236 of the key 6 are positional, with relatively close clearance 17, to the keyway 214, 216 of the blade and thus rotation of the key 6 with respect to the blade 2 is substantially prevented. The amount of clearance 17 which is provided will depend on the particular configuration. In one embodiment the clearance 17 is between about 0.0005 inches (about 0.01 millimeters) and about .0015 inches about (0.04 millimeters). Thus, since the key 6 in the relaxed or locked configuration is prevented from clockwise rotation 239 with respect to the plate 1 and is prevented from any rotation with respect to the blade 2, the effect is that the intersection of contact surfaces 220a, 220c with keyway surfaces 23a, 23b prevents substantially any clockwise rotation of the blade 2 with respect to the handle. Preferably the key locking mechanism does not prevent opposite (counterclockwise) rotation because of the angles 228a, 228b.

Counterclockwise rotation 241 of the blade 2 with respect to the handle is prevented by the bearing of the contact surface 9a of adjustable stop device 9 against stop surface 15 of the blade 2. Thus, since both clockwise rotation 239 and counterclockwise rotation 241 with respect to the handle is prevented, the blade is prevented from any substantial rotational motion with respect to the handle (substantially) while the key 6 is in the relaxed or locking position. In this context, "substantial" prevention of rotational movement means no rotational movement of a magnitude that would be noticeable during ordinary use of the knife and is preferably less than zero degrees ten minutes of angle (0.degree. 10') and more preferably less than zero degrees zero minutes ten seconds of angle (0.degree. 0' 10").

FIG. 6A depicts an operation of the knife. In the depicted embodiment, a user grasps the handle, e.g., with the left hand 602. The open position of the blade is shown in FIG. 6A by phantom lines. When it is desired to close the knife, the user grasps the key locking mechanism, e.g. with the right or left hand 604, compressing the key locking mechanism between the thumb 606 and forefinger 608 to move the key 6 to the position depicted in FIG. 8 such that the key devices 234, 236 reside solely within the blade keyway 214, 216 and are clear of the right plate keyway 238, 240. In the depressed configuration, the key contact surfaces 220a, 220c no longer contact the plate keyway contact surfaces 23a, 23b and, as a result, clockwise rotation of the key (and thus the blade) is no longer prevented. The user then can rotate the key mechanism in a clockwise direction 239, e.g. by moving the hand 604 in direction 610 (which is shown in FIG. 6A as a counterclockwise movement since FIG. 6A is a view along line-of-sight 252 while FIG. 5 is a view along line-of-sight 254). As the key 6 rotates, contact surfaces 220c, 220a push against blade keyway surfaces 218c, 218a respectively, as shown in FIG. 7 thus carrying the blade 2 in a similar movement 612 towards the closed configuration depicted in FIG. 3. Rotation of the key 6 and blade 2 continue until the blade stop surface 232 contacts the stop device 8 as depicted in FIG. 9. Stop device 8 is configured and/or adjusted such that when the blade stop surface 232 contacts the stop device 8, the key 6 will have rotated to a position such that the key contact surfaces 220b, 220d are substantially aligned with plate keyway contact surfaces 22a, 22b, allowing the key 6, upon the user releasing pressure between the thumb and forefinger 606, 608, and under the urging of the spring 208, to relax or return to the position situated partially in the plate keyway 238, 240 as depicted in FIG. 6B. Since surfaces 220b, 220d are inclined at angles 228b, 228a with respect to planes 224a, 224b (as described above) the blade 2, when it reaches the closed configuration, has traveled through a rotational angle 902 which is less than 180.degree.. This permits the designer of a knife to select the angle 902 desired for the particular use rather than being constrained to a closed position which is 180.degree. from the open position. This, for example, permits the design of a folding knife which provides the positive locking feature desired but permits the back edge 904 of the blade to more easily protrude above the handle in the closed configuration. providing a rotational angle 902 of less than 180 degrees places fewer constraints on the design of the spacer and, in particular permits the spacer to be provided with a depth 903 which is greater than that possible when the angle 902 is 180 degrees, at least if the knife is designed with a pleasing appearance and without excessive or unnecessary weight. Greater depth 903 for the spacer provides greater stability to the knife, such as better maintenance of the plates in the desired, usually parallel, relationship.

In the closed and locked configuration depicted in FIG. 9 rotation in the clockwise direction 906 is prevented by contact of the stop device 8 with the blade stop surface 232 and rotation in the counterclockwise direction 908 is prevented by contact of key contact surfaces 220b, 220d with plate keyway contact surfaces 22a, 22b respectively. Since the key 6 is fitted in the keyway of the blade with relatively close tolerance as depicted in FIG. 10, preventing rotation of the key 6 with respect to the handle also prevents rotation of the blade 2 with respect to the handle in the closed configuration.

When it is desired to open the knife from the closed configuration, the user grasps the key locking mechanism, e.g., as depicted in FIG. 6A compressing the key locking mechanism to move the key 6 from the position depicted in FIG. 6B to the position depicted in FIG. 8 such that keys 234, 236 reside solely within the blade keyway 214, 216 and are clear of the right blade keyway 238, 240. In the depressed configuration, the key contact surfaces 220b, 220d no longer contact the plate keyway contact surfaces 22a, 22b and, as a result, counterclockwise rotation (in the view of FIG. 9) of the key (and thus of the blade) is no longer prevented. The user then can rotate the key in a counterclockwise direction 908, e.g. by moving the hand 604a in direction 614. As the key 6 rotates, contact surfaces 220b, 220d push against the blade keyway surfaces 218b, 218d respectively, as depicted in FIG. 10, thus carrying the blade 2 in a similar movement 614 towards the open configuration depicted in FIG. 4. Rotation of key 6 and blade 2 continue until the blade stop surface 15 contacts the stop device 9 as depicted in FIG. 5. Stop device 9 is configured and/or adjusted such that when the blade stop surface 15 contacts the stop device 9, the key 6 will have rotated to a position such that the key contact surfaces 220a, 220c are substantially aligned with the plate keyway contact surfaces 23a, 23b, allowing key 6, upon the user releasing pressure between the thumb and forefinger, 608, 606, and under the urging of spring 208, to relax or return to the position situated partially in the plate keyway 238, 240 as depicted in FIG. 6B. In this opened and locked configuration, depicted in FIG. 5, rotation in the counterclockwise direction 241 is prevented by contact of the stop device 9 with the blade stop surface 15 and rotation in the clockwise direction 239 is prevented by contact of key contact surfaces 220a, 220c with plate keyway contact surfaces 23a, 23b respectively. Since the key 6 is fitted in the keyway of the blade with relatively close tolerance 17 as depicted in FIG. 7, preventing rotation of the key 6 with respect to the handle also prevents rotation of the blade 2 with respect to the handle in the open configuration.

FIGS. 11 and 12 depict another embodiment of the invention. In the embodiment of FIGS. 11 and 12, the key 12 is configured to provide more than two effective anti-rotation contact surfaces in the closed position and more than two effective anti-rotation contact surfaces in the open position. Thus, in the embodiment of FIG. 5 the key 6 has four contact surfaces, 220a', 220a", which contact corresponding plate keyway contact surfaces 24a', 24a"and also has two further key contact surfaces 220c', 220c"which abut plate keyway contact surfaces 24b', 24b"respectively when the blade 13 is in the extended position and the key 12 is in the locking position. As shown in FIG. 12, the key 12 also has four key contact surfaces 220d', 220d", 220b', 220b" configured to contact plate keyway contact surfaces 16a'16a"16b', 16b"to prevent counterclockwise rotation when the blade 13 is in the closed position. It is believed that by providing additional contact surfaces as depicted in FIGS. 11 and 12, the strength provided for holding the blade in the extended or folded configuration is enhanced.

FIG. 11 also depicts a configuration in which a stop device 11 for preventing counterclockwise rotation when the blade is extended is coupled, preferably adjustable coupled, to the blade 13, rather than being coupled to the handle. The stop device 11 is configured and/or adjusted such that when the blade is in the desired extended position the contact surface 11a will contact a stop surface 18a formed in a cavity 18 of the handle and preferably, the spacer 3. As depicted in FIG. 12, a stop device 10, preferably adjustable, is coupled to blade 13 and positioned or adjusted to prevent clockwise rotation 906 of the blade 13 when it is in the closed configuration by bearing against a stop surface 1202 of the handle, preferably formed in the spacer 3. Because the side plate keyway contact surfaces are parallel to each other, the configuration of FIGS. 13 and 14 may be used to retrofit an existing handle assembly to permit introduction of a new blade shape.

In the various embodiments described thus far, two different devices are used for preventing rotation in the clockwise direction and counterclockwise direction respectively. For example, in the embodiments of FIGS. 5 and 9, the key and keyway prevent clockwise rotation in the extended configuration and counterclockwise rotation in the folded configuration while the stop devices 8 and 9 prevent counterclockwise rotation in the extended configuration and clockwise rotation in the folded configuration. It is believed preferable according to at least one embodiment of the invention, that integral surfaces of the key and keyway are not used for both clockwise antirotation and counterclockwise antirotation in a given blade configuration, since this is believed to contribute to rotation or play in the locked blade position or other undesirable performance characteristics, at least for normal machining and tolerance parameters.

FIGS. 13 and 14 depict another embodiment of the invention in which the plate keyway surfaces 1422a, 1423a, 1422b are co-planer or parallel with one another rather than be offset at angles 228a, 228b as depicted in FIG. 2. In this embodiment, the key 20 provides key devices with contact surfaces 21a, 21b that are offset from adjacent contact surfaces 21a', 21b'. This is depicted, e.g., in the view of FIG. 13. According to this embodiment, when the blade is in the extended position as depicted in FIG. 14, the operation is similar to that depicted in FIG. 5, i.e., clockwise rotation 239 is prevented by interaction of surfaces 220a, 220c with keyway contact surfaces 1423a, 1423b respectively and counterclockwise rotation 241 is prevented by abutment of stop device 9 with stop surface 15. However, when the blade 2 is rotated to the closed position, offset surfaces 21a, 21b will contact plate keyway contact surfaces 1422b, 1422a respectively to prevent counterclockwise rotating 241. Although plate keyway contact surfaces 1422b, 1422a are respectively parallel to keyway contact surfaces 1423a, 1423b, the angled or offset nature of the surfaces 21a, 21b permit locating the blade 2 in a folded configuration which is less than 180.degree. rotated from the extended position depicted in FIG. 14.

FIG. 15 depicts another embodiment of the invention in which handle plates or scales 7' are positioned on he exterior surfaces of the sideplates 1, 7. In the depicted embodiment, the handle plates (or scales) are held to the sideplate preferably by threaded fastners 1502, 1504 rather than e.g. glue. By making the handle plates removable, it is possible for the user to easily replace or modify the handle plates, e.g. by whittling. A number of materials can be used for the handle plates, including plastic, wood, bone, ceramic, metal, and resin. By making the handle plates removable, this embodiment provides for ease of assembly at the time of manufacture and ease of after-market retrofit, repair, modification or maintenance.

In light of the above description, a number of advantages of the present invention can be seen. The present invention provides a folding knife which achieves secure locking in at least the extended position and, preferably, also a folded condition with substantially no rotation of the blade with respect to the handle when in the locked condition while still providing a device which is relatively easy to design, manufacture, repair and maintain. The invention can have adjustable stops, preferable user-adjustable, to make the device not only easy to manufacture, but also to make the device easy to maintain e.g., to compensate for wear by adjusting set-screws 8, 9. Preferably, the device is ambidextrous, i.e. can be easily operated by using either the right hand or the left hand to depress the key locking mechanism.

The present invention provides for the sheathing of the blade and the handle quickly and safely and for the blade to be quickly made available in a secure and firm manner when unfolded for use. In some embodiments the mechanism controlling the knife blade is configured to avoid inadvertent unlocking. The present knife device is readily operated between its two extreme positions, is safe, simple, accurate and long-lived. Further, the present invention provides the above-described advantages and various other advantages, while being relatively easy and economical to design, manufacture, maintain and repair.

A number of variations and modifications of the present invention can also be used. It is possible to use some aspects of the invention without using other aspects. For example, it is possible to provide a locking knife which is configured to have a blade rotation other than 180.degree. between the extended and folded configuration without providing set screw-type stop devices. It is possible to provide separate anti-rotation devices for clockwise and counterclockwise motion without providing for rotating of the blade via rotating the carrier and key. Although in the depicted embodiments a key and keyway mechanism is used for preventing on in a first rotational direction while stop devices are used for preventing rotation in a second rotational direction, other mechanisms can be used for these purposes than those depicted. A number of different key and keyway shapes can be used, as non-exhaustively illustrated in the embodiments of, e.g., FIG. 5 and the embodiment of FIG. 11. For example, a key and keyway having more or fewer than the depicted two key devices or which has key devices shaped differently than those depicted (e.g. cylindrical, tapering, and the like can be used. Although the key is depicted as being held in place by a carrier and screw-threaded nut, other ways of maintaining a key in a desired area can be provided, including stamping, press fit, flanges and the like. A biasing or urging means other than helical spring 208 can be provided such as a compression spring, a leaf spring, a resiliently deformable plastic or other material and/or hydraulic or pneumatically-forced systems. In addition to a rotational key device, a rotational device with other or additional ways of coupling selectively to the handle can be provided such as a device for radially expanding and compressing against a circumferential surface, a rachet or a cam device. Similarly, a number of stop, preferably adjustable stop, devices can be provided, e.g. as non-exhaustively illustrated in FIGS. 5 and 11. Other types of stop devices could be provided, such as stop devices that are adjustable by a rack and pinion device, a lateral set-screw device, or a cam with respective stop devices being attachable in a number of fashions to either the blade or the handle including coupling via a screw coupling as depicted, or via dovetail or mortise and tenon, pin and hole or other coupling configurations. Although stop surfaces, e.g. stop surface 15, are disclosed as being formed by cut,out portions, they can also be formed as, e.g. pockets or cavities.

The knife according to the present invention could be made out of a number of materials, including metal, plastic, fiberglass, reinforced resins and the like. Preferably, the blade 12 is formed of steel. Preferably, the plates and spacer are formed of steel, aluminum or titanium. Preferably, the carrier, key and nut are formed of stainless steel or carbon steel (preferably plated).

Although the present invention has been described by way of preferred embodiments and certain variations and modifications, other variations and modifications can also be used, the invention being defined by the following claims: