Safety lock mechanism for folding knives

A safety lock mechanism for a folding knife includes a lock plate movably coupled to a handle of the knife for movement along a first direction from an engaged position to a disengaged position, the lock plate biased towards the engaged position. A rocker element is coupled to the lock plate for movement from a locked position to an unlocked position and is configured to prevent translational movement of the lock plate to the disengaged position when the rocker element is in the locked position. A control button coupled to the rocker element allows a user to move the rocker element from the locked position to the unlocked position and to move the lock plate towards the disengaged position to thereby release a blade of the knife.

BACKGROUND

1. Technical Field

This disclosure generally relates to folding knives, and in particular to folding knives having safety lock mechanisms.

2. Description of the Related Art

Folding knives enjoy wide popularity, particularly among sportsmen, campers, hikers, and many others engaged in outdoor activities. 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. Many folding knives also include a locking mechanism to maintain the blade in the open position and/or the closed position. A locking mechanism is particularly advantageous with folding knives having an assisted opening mechanism and automatic knives. Examples of folding knives, including folding knives with locking mechanisms, may be found in U.S. Patent Publication No. 2007/0180702, the entire disclosure of which is herein incorporated by reference for all purposes.

One difficulty that has been encountered is that the locking mechanism of many knives is prone to inadvertent disengagement of the lock which can lead to unintended deployment of the knife blade from a closed position or unintended closure from an open position. Such unintended deployment and closure of the knife blade presents a safety hazard to users, particularly in the case of an automatic knife (i.e., switchblade) or a knife having an assisted opening mechanism.

BRIEF SUMMARY

According to various embodiments, a safety lock mechanism of a folding knife effectively prevents unintended movement of a knife blade from a closed or open position. According to one embodiment, the safety lock mechanism has a lock plate movably coupled to a handle of a knife for movement along a first direction from an engaged position to a disengaged position, the lock plate biased towards the engaged position. A rocker element is movably coupled to the lock plate for movement from a locked position to an unlocked position and is configured to prevent translation of the lock plate to the disengaged position while in the locked position.

A detent mechanism is configured to cooperate with the rocker element to bias the rocker element toward the locked position and unlocked position while the rocker element is in the locked position and unlocked position, respectively.

A control button coupled to the rocker element and accessible to a user at an outer side of the handle permits the user to move the rocker element to the unlocked position and the lock plate to the disengaged position to thereby release a blade of the knife.

DETAILED DESCRIPTION

For the purposes of clarity and ease of comprehension, directional terms such as, for example, top, bottom, right, and left may be used in describing embodiments, and will be with reference to elements as they appear on the figures. Where elements are described using terms such as inner or outer, this is with respect to a central plane of the knife, i.e., a plane that lies parallel to, and substantially centered between, the first and second frame members. Thus, a side of an element that lies closer to that center plane than another side of the element may be described as the inner side of the element.

Elements that are, in the illustrated embodiment, substantially identical will be identified by identical reference numbers. Where it is necessary to distinguish between such identical elements in the description, letters will be used. Fasteners, which may be screws, rivets, pins, or other suitable devices such as are well known in the art, are not illustrated for purposes of clarity and ease of comprehension.

An embodiment will be described with reference toFIGS. 1-7.

The knife10includes a handle40and a blade20. The handle40includes first and second frame members42,44arranged in a spaced-apart relationship, with a space, or blade channel58, between them. First and second handle overlays52,54are affixed to outer faces of the first and second frame members42,44, respectively, by fasteners (not shown). A spacer130is positioned between the first and second frame members42,44at a rear end of the handle40. A stop pin124is positioned between the first and second frame members42,44at a front end of the handle40.

The blade20is coupled to the handle40so as to rotate around a pivot axis A with respect to the handle40, between an open position, as shown inFIGS. 1,2,4and5, in which the sharp edge of the blade20is exposed, and a closed position, as shown, for example, inFIGS. 6 and 7, in which the blade lies with the sharp edge within the channel58, between the first and second frame members42,44. In other embodiments, the blade20may be positioned in the blade channel58to a greater or lesser degree than that shown in the pictured embodiment. The blade20includes a blade pivot aperture22formed coaxially with the pivot axis A, and control apertures24,26positioned some distance from the pivot axis A. The pivot aperture22and the control apertures24,26traverse the blade20. First and second control pins34,36are positioned in the control apertures24,26, respectively.

Frame pivot apertures48are provided in each of the first and second handle frame members42,44, and each of the first and second handle overlays52,54is provided with an overlay pivot aperture56. The pivot apertures48and56are positioned so as to be substantially coaxial with the pivot axis A when the knife10is properly assembled.

A safety lock mechanism60is provided to retain the blade20in the open and closed positions and prevent inadvertent blade movement. The safety lock mechanism60includes a lock plate80having a notch86, with first and second sides88,90, and positioned, in the pictured embodiment, in a lock cavity46formed in the first frame member42. The lock cavity46is sized to permit translational movement of the lock plate80, and biasing means102are provided to bias the lock plate80substantially toward the pivot axis A. In the pictured embodiment, the bias means102comprise springs104and guide rods106, but a wide variety of mechanisms may be employed as biasing means, and substituted for the springs, such as, for example, flexible rods, leaf springs, torsion springs, etc. The bias means may be retained within a separate retaining structure, such as, for example a guide plate96, or alternatively, may be retained within a cavity, groove, or the like, formed in the first handle frame member42.

The safety lock mechanism60further includes a rocker element70movably coupled to the lock plate80for movement between a locked position and an unlocked position. In the illustrated embodiment, the rocker element70has first and second ends72,74and is positioned in an aperture82of the lock plate80. The aperture82is sized and shaped to substantially prevent relative translational movement between the lock plate80and rocker element70in a direction substantially parallel to the direction of travel of the lock plate80and to simultaneously allow relative rotational movement therebetween. The rocker element70is allowed to rotate about an axis passing through a center portion of the rocker element70, the location of the axis corresponding to the center78of circular arc segments of the rocker element70. Although the present embodiment illustrates the rocker element70movably coupled to the lock plate80for rotational movement therebetween, other forms of movably coupling the rocker element70to the lock plate80are feasible. For example, in an alternate embodiment, the rocker element70may be movably coupled to the lock plate80to allow relative translational movement therebetween in a direction substantially perpendicular to the direction of travel of the lock plate80.

The first end72of the rocker element70is coupled to a control button100via a control button aperture76for manually moving the rocker element70from a locked position to an unlocked position. The second end74of the rocker element70cooperates with a detent mechanism110to selectively hold the rocker element70in the locked and unlocked positions. In the illustrated embodiment, the detent mechanism110comprises a detent ball112and a detent spring114retained in a channel of the lock plate80, but a wide variety of detent mechanisms may be employed, and substituted for the detent ball and spring, such as, for example, a spring steel lever and notches.

Operation of the safety lock mechanism60will be described with reference, in particular, toFIGS. 4 through 7. The first frame member42is provided with an arcuate pin race50formed in the inner face of the first frame member42that is positioned coaxially with the pivot axis A. The pin race50and the lock cavity46are formed in opposite faces of the frame member42, but are of depths such that they intersect in an area where they overlap, as can be seen inFIG. 3, where a portion of the race50is visible inside the lock cavity46. At the location where they overlap, the pin race50forms an aperture through the frame member42. The cross-section ofFIGS. 4 through 7is taken through the first frame member42at a depth that shows both the lock cavity46and the pin race50.

As previously described, the blade20is provided with control apertures24,26. First and second control pins34,36are positioned in respective control apertures24,26, and extend from the blade20into the pin race50. As the blade20rotates between the open and closed position, the control pins34,36slide within the pin race50in an arc around the pivot axis A. In this embodiment, the pin race50forms a complete path around the frame pivot aperture48. Rotational travel of the blade20is limited by a first blade stop28and a second blade stop30that are positioned to engage a stop pin124that is coupled between the first and second frame members42,44when the knife is in the open and closed position, respectively. In an alternate embodiment, the pin race50forms a partial path having first and second ends that serve as rotation stops to limit movement of the blade20to an arc of travel between the open and closed position.

FIG. 4, which shows the knife10with the blade20in the open position, shows the notch86of the lock plate80in engagement with the first control pin34. The lock plate80is pressed into engagement with first control pin34by springs104. It can be seen that, as viewed inFIG. 4, the first control pin34must rotate in a counterclockwise direction around the pivot axis A when the blade20is moved from the open position toward the closed position. The first side88of the notch86is shaped such that, while the lock plate80is in an engaged position in which the notch86is engaged with the first control pin34, it will prevent movement of the blade20toward the closed position. Rotational force applied to the blade20is transferred to the first control pin34, and thence to the lock plate80at a vector that is nearly perpendicular to the direction of movement of the lock plate80. Thus, the lock plate80binds against the side of the lock cavity46and does not permit passage of the first control pin34. In another embodiment, the first side88of the notch lock plate is configured to act as a detent, allowing the blade to be moved away from the open position when sufficient force toward the closed position is applied to the blade20. The shape of the first side90and the biasing force of the springs104can be selected to control the degree of force necessary to overcome the resistance of the lock plate80to move blade20.

As shown inFIG. 4, the lock plate80is held in the engaged position by springs104and prevented from translating to a disengaged position by the rocker element70when the rocker element70is rotated to a locked position. The lock plate80is prevented from translating to the disengaged position by an island stop64that is positioned in the lock cavity46of the first frame member42and configured to cooperate with the second end74of the rocker element70. The island stop64may be integral with the first frame member42, such as, for example, leaving material in place when milling the lock cavity46, or may be coupled to the first frame member42, such as, for example by fastening, welding, etc. It may also be a pin that is pressed into a recess in the frame member42and extends out as shown inFIG. 3. Conversely, when the rocker element70is in an unlocked position, as shown inFIG. 5, the lock plate80is able to translate away from the pivot axis A towards the disengaged position.

In order to move the blade20away from the open position, it is necessary that the rocker element70be manually moved to the unlocked position and the lock plate80be moved from the engaged position, as shown inFIG. 4, to the disengaged position, as shown inFIG. 5, wherein the notch86of the lock plate80is out of engagement with the first control pin34. A user does this by first moving the control button100in a direction toward the back of the knife. To move the rocker element70to the unlocked position, the user applies a force to the control button100sufficient to overcome a first bias applied to the rocker element70by the detent mechanism110. Once in the unlocked position, the rocker element70is held in place by a second bias applied to the rocker element70by the detent mechanism110. With the rocker element70no longer in contact with the island stop64, the lock plate is unlocked. In the unlocked position, the lock plate80is able to move in a direction away from the pivot axis A, thereby allowing the blade20to move away from the open position.

When the blade20is moved into the fully open position from being closed, the first control pin34approaches engagement with the lock plate80, and pushes against an end face92of the lock plate80, applying force at a vector that easily moves the lock plate80rightward a distance sufficient to permit passage of the first control pin34. Thus, as configured in the present embodiment, the blade20moves easily into the fully open position and is locked there until it is manually released for movement toward the closed position. Once the blade20is in the open position, the rocker element70may be manually moved to the locked position by moving the control button100in a direction away from the back of the knife, thereby preventing inadvertent displacement of the lock plate80and closure of the blade20. To move the rocker element70to the locked position, the user applies a force to the control button100sufficient to overcome the second bias applied to the rocker element70by the detent mechanism110.

In one embodiment, the first blade stop28of the blade20defines the limit of travel of the blade20in the clockwise direction. When the blade is moved to the open position, the first blade stop28makes contact with the stop pin124, which prevents further movement. The notch86of the lock plate80has a location and shape such that the first side88of the notch86engages the first control pin34before the lock plate80reaches the leftmost end of the lock cavity46. This allows the lock plate80, in engagement with the first control pin34, to cooperate with the first blade stop28of the blade20, in engagement with the stop pin124, to provide a solid lock to the blade20, substantially without play.

FIG. 6, which shows the knife10with the blade20in the closed position, shows the notch86of the lock plate80in engagement with the second control pin36and shows the rocker element70in the locked position. The lock plate80is pressed into engagement with the second control pin36by springs104. It can be seen that, as viewed inFIG. 6, the second control pin36must rotate in a clockwise direction around the pivot axis A when the blade20is moved from the closed position toward the open position.

In order to move the blade20away from the closed position, it is necessary that the rocker element70be manually moved to the unlocked position and the lock plate80be moved from the engaged position, as shown inFIG. 6, to the disengaged position, as shown inFIG. 7, wherein the notch86of the lock plate80is out of engagement with the second control pin36. A user does this by first moving the control button100in a direction toward the back of the knife. As previously described, to move the rocker element70to the unlocked position, the user applies a force to the control button100sufficient to overcome a first bias applied to the rocker element70by the detent mechanism110. Once in the unlocked position, the rocker element70is held in place by a second bias applied to the rocker element70by the detent mechanism110. In the unlocked position, the lock plate80is able to move in a direction away from the pivot axis A, thereby allowing the blade20to move away from the closed position.

On the other hand, when the blade20is moved into the closed position, the second control pin36approaches engagement with the lock plate80, and pushes against a sloped surface94of the lock plate80, applying force at a vector that easily moves the lock plate80rightward a distance sufficient to permit passage of the second control pin36. Thus, as configured in the present embodiment, the blade20moves easily into the fully closed position and is locked there until it is manually released for movement toward the open position. Once the blade20is in the closed position, the rocker element70may be manually moved to the locked position by moving the control button100in a direction away from the back of the knife, thereby preventing inadvertent displacement of the lock plate80and deployment of the blade20. As previously described, in order to move the rocker element70to the locked position, the user must apply a force to the control button100sufficient to overcome the second bias applied to the rocker element70by the detent mechanism110.

In one embodiment, the second side90of the notch86is shaped such that the lock plate80will resist movement of the blade20toward the open position until the lock plate80is manually moved out of engagement with the second control pin36, in a manner similar to that described above with reference to the first side88. Such an embodiment is particularly beneficial for a switchblade or automatic type knife that is spring biased to open quickly when the second lock plate80is translated to the disengaged position.

In another embodiment, the shape of the second side90is selected such that when sufficient rotational force is applied to the blade20, the second control pin36pressing against the second side90of the notch86will drive the lock plate80in a rightward direction against the biasing force applied by the springs104, thereby releasing the blade20to move toward the open position. Thus, the safety lock mechanism60acts as a detent mechanism to releasably hold the blade in the closed position. The shape of the second side90and the biasing force of the springs104can be selected to control the degree of force necessary to overcome the resistance of the lock plate80to move blade20.

According to one embodiment, the required biasing force is selected such that, in normal operation, when a user applies a force sufficient to overcome the resistance of the lock plate80, the same force is sufficient to move the blade20all the way to the open position. The force applied to start movement of the blade20from the closed position toward the open position will cause the blade20to complete the movement without further effort. Thus, a user may press against a thumb stud or some other feature of the blade (not shown) until the blade20begins to move, and the blade will thereafter complete the movement independently.

An example of a suitable blade feature against which a user may press to open the blade20is an element sometimes referred to as a flipper. This is an enlarged portion of the blade that extends from a back part of the blade20when the blade20is in the closed position, such that pressure against the enlarged portion will move the blade20away from the closed position. A number of terms are used in the art to refer to this enlarged portion, including flipper, trigger, kicker, ridge, etc. One example of such a feature is described in U.S. Pat. No. 6,338,431, which is incorporated herein by reference, in its entirety.

In some embodiments, an indicator66is provided on the handle40to visually indicate when the rocker element70is in the locked or unlocked position. For example, in one embodiment, the indicator66is a red arcuate region provided around a button aperture68of the first handle overlay52, as can be seen inFIG. 3.

Some embodiments do not include all the elements of the disclosed embodiments, and some combine elements disclosed here with more conventional aspects. For example, in the embodiment shown, the blade channel58extends through the knife10, from the back side to the front side, with only the blade20, spacer pin130, and the stop pin124positioned between the first and second frame members42,44. Such an arrangement is not essential. Other embodiments may include a channel that is open only at the front of the knife.

Some of the features of the embodiments disclosed above are grouped into elements and sub-elements for convenience. For example, a safety lock mechanism is described as including a number of individual components. Where claims recite similar elements, such claims should not be construed as including the same sub-elements unless the sub-elements are explicitly recited as members of the recited elements.