Safety for knife-blade lock

Abstract: A knife (10) has a folding blade (12), a blade lock (28) in the form of a leaf spring (24a), and a safety (30) for preventing unlocking of the lock (28). One form of safety (30) has a carrier in the form of an elongate arm (34) mounted on the knife handle (18). A stud (32) is positioned on an inside surface of one end of the arm (34). A contact surface (34b) is formed on an outside surface of the arm (34) opposite from the stud (32). The other end of the arm (34) is pivotably attached to the handle (18) of the knife (10). The arm (34) may be swung from a release position, unobstructive of the lock (28), to a safety position in which the presence of the stud (32) prevents unlocking the lock (28). The carrier (54) may be spring (56) biased toward the release position, and may have limited travel away from the handle (18) to the release position. The carrier may also be a slide (64) or a rotating disk (74).

Description: The present invention relates to the field of a lock for locking a knife blade in an open position, and more particularly to a knife comprising a safety for keeping such a blade lock in a locking position. One form of conventional pocket knives are built with a handle and one or more folding blades. The blades in such knives are closed simply by pressing on the back of the blade and rotating the blade to a closed position in the knife handle. Such knives are known for their ability to close when being used if a pressure is inadvertently applied to the back of the blade. In order to prevent this from happening, and thereby to allow use of both edges of the blade, locks were developed for locking a blade in an open position. This is commonly provided by a lock element that is spring biased to snap into position adjacent to the hinged end of the blade when the blade is opened. A projecting portion of the lock element or other release mechanism is manipulated to move the lock element away from the blade swing path so that the blade can be closed (see for example GB-A-2 208 212). Folding knives having such locking blades have become common. However, because the lock feature is defeated by manipulation of an element on the knife handle, it is not unusual for the lock to be defeated inadvertently during use of the knife. If the person using the knife is unaware that the blade is unlocked, it can close unintentionally when a backward force is applied to the knife blade in what is intended to be a safe procedure. The use of knives with locking blades has therefore not been met with universal acceptance because of the possibility of inadvertently defeating the locking feature during use The present invention overcomes this limitation of the prior art by providing a safety for the locking feature of a knife with a folding blade. Such a safety is selectively engageable for preventing movement of a lock element from a locking position. When such a safety is engaged, the knife blade will not inadvertently become unlocked with manipulation of the release element of the lock. In general terms, then, the present invention provides a safety having a stud that is movable between a safety position in which the stud prevents movement of the lock from the lock position, and a release position in which the stud does not prevent movement of the lock from the lock position. The stud is mounted on a carrier, such as a member or bar, which is also referred to as a mounting means, that is movable in a way that moves the stud between the safety and release positions. An activation means, such as a lever or contact surface on the carrier, is coupled to the mounting means in a position exposed for manual movement of the carrier and the stud. The present invention provides a knife as claimed in claim 1. Various embodiments of the invention are possible, some of which are described below. These embodiments all function on a knife in which the lock is a finger biased like a leaf spring. The finger rides against the side of the blade when the blade is closed and moves in line with the blade when the blade is opened. In order to close the knife the finger must be moved from in line with the blade. A safety made according to a first preferred embodiment of the invention has a carrier in the form of an elongate bar or arm mounted on the knife handle. A stud is positioned on an inside surface of one end of the safety arm. The contact surface is formed on an outside surface of the arm opposite from the stud. The other end of the arm is pivotably attached to the handle of the knife. A recess in the knife handle receives the safety when the stud is in either the safety position or the release position. In another embodiment, the carrier slides in a slit in the handle between the safety and release positions. In yet another embodiment, the carrier is an arm pivotably attached to the handle, similar to the first embodiment. However, in this embodiment, the contact surface is close to the handle in the safety position and pivots away from the handle to the release position. A spring biases the carrier toward the release position. When a person grips the handle, the carrier is held in the safety position. This embodiment, as does the first embodiment, has the particular advantage of providing the user with the added safety of holding the safety in the safety position during use, preventing possible inadvertent release of the knife lock. A final embodiment has a carrier in the form of a washer mounted on the blade hinge between the handle and blade. Rotation of the carrier moves a stud mounted on an outer edge of the carrier between the safety and release positions. It will be appreciated that these safeties provide means for locking a blade lock in a locked position. This prevents inadvertent unlocking of the lock, particularly when the lock is designed to be unlocked by a simple movement relative to the handle. An appreciation of these and other features and advantages of the present invention and a more complete understanding of the invention may be achieved by studying the following description of the preferred embodiments and by referring to the accompanying drawings. FIG. 1 is a side view of a knife having a safety made according to the invention, with the safety in a release position. FIG. 2 is an inside view of the knife of FIG. 1 showing the side of the knife with the safety. FIG. 3 is an enlarged fragmentary bottom view of the knife of FIG. 1 showing the blade, hinge, handle, lock, and safety. FIG. 4 is a view similar to FIG. 1 showing the safety in the safety position. FIG. 5 is an inside view similar to FIG. 2 of the knife of FIG. 4. FIG. 6 is a side view of a knife having a second embodiment of a safety made according to the invention. FIG. 7 is also a side view of a knife having yet another embodiment of a safety made according to the invention. FIG. 8 is a side view of a knife having a fourth embodiment of a safety. As has been mentioned, the invention provides a safety for a knife having a folding blade and a lock that locks the blade in an open position. The safety secures the lock in the lock position. FIGs. 1-3 illustrate a knife 10 having a blade 12 that pivots about an axle or hinge pin 14 defining a blade axis 16 between open and closed positions. These figures show the blade in an open or unfolded condition. A handle 18 that supports hinge pin 14 has outer side panels or frames 20 and 22, and associated liners 24 and 26. The liners in the form of plate elements conventionally were made of brass, but more recently are being made of titanium. The side of the handle seen in FIGs. 1 and 2 is referred to as the right side. The hinge end of the blade opposite from the tip has a generally straight edge 12a. A lock 28 formed out of liner 24 consists of a finger 24a that is biased toward the blade, like a leaf spring. Finger 24a has an end edge 24b that conforms to blade edge 12a. When the blade is closed or in a folded position, finger 24a is flush against the side of the blade, in what is referred to as an unlocked position, and the blade is free to rotate. When the blade is pivoted to the fully open position, as is shown in the figures, the free end of finger 24a snaps into locking position in line with the blade with finger edge 24b adjacent to blade edge 12a. Without moving finger 24a to the side of blade 12, the blade cannot be moved from the open position when the finger is in the locking position. Finger 24a typically also has an exposed region, such as region 24c that facilitates grasping the finger for movement out of the way when it is desired to return the blade to the closed position. It will be appreciated that if the handle is gripped in the hand of a person and the hand is moved around the handle in a way that moves the finger toward the unlocked position, lock 28 will be defeated and the blade would be free to close, possibly against the person's hand. The description so far is of a conventional folding knife with a locking blade. In order to allow a person the option of securing the lock in the locking position, knife 10 is provided with a safety 30 made according to the invention. Safety 30 includes a stud 32 mounted to one end of an elongate arm 34. The other end of arm 34 is mounted to right side panel 20 of the handle for pivoting about a safety pivot axis 36. Since arm 34 in effect simply carries the stud between the safety and release positions, it is also referred to as a carrier. A recess 38 in the handle receives the arm so that the safety does not significantly alter the overall configuration or shape of the handle. Arm 34 pivots in a plane parallel to the blade. A first slot 40 exists in handle panel 20 in line with the position of the stud to allow the stud to reach the safety position, as represented by the position of the stud in dashed lines in FIG. 3 and as shown in FIGs. 4 and 5. Correspondingly, a second slot 42 also exists in panel 20 to accommodate the position of the stud in the release position, as is shown in FIGs. 1 and 2, and in solid lines in FIG. 3. In order to not interfere with the movement of the lock when the stud is in the release position, a slot 44, in line with slot 42, is also formed in the exposed edge of finger 24a. It also would be possible to change the size of the finger, or change the resting position of the stud. A textured projection 34a has an exposed contact surface 34b that is opposite from stud 32 on arm 34. Projection 34a preferably extends slightly out beyond the surface of the handle to facilitate contact by the hand of a person manipulating the safety. Projection 34a is also referred to as manipulation means. With the stud positioned in the release position, lock 28 is operable as it would be without safety 30. Thus, finger 24a can be moved from the locking position, shown in solid lines in FIG. 3, to the unlocked position, shown in dashed lines in the same figure. Blade 12 may then be folded closed. The blade must be open and locked in order to engage safety 30. Arm 34 is pivoted about axis 36 until stud 32 rests in handle slot 40 with the head of the stud adjacent to the side of finger 24a. The finger is thereby prevented from being moved toward the unlocked position. Safety 30 has the further advantage of being secure during use. That is, while the handle is being gripped by a person, the arm 34 is held in handle recess 38, thereby preventing inadvertent movement of the safety to the release position. Any force applied to grip region 24c will not cause it to move into the unlocked position due to the presence of the stud. This additional security in use of knife 10 is made possible by the fact that it is necessary to move the end of arm 34 having stud 32 away from the handle in order to change the position of the stud to the release position. FIGs. 6, 7 and 8 illustrate knives having three different configurations of safeties but with locks that are substantially the same as lock 28. FIG. 6 shows a knife 50 in which a safety 52 is formed of an arm 54 similar to arm 34, except that the arm only pivots a few degrees away from the safety position, to a release position, such as the position shown in dashed lines. A spring 56 biases the arm toward the release position away from the knife. When in the release position, then, the arm extends away from the knife and may interfere somewhat with its use. However, as with safety 30, when the handle is gripped with the blade open, the safety is forced into and held in the safety position. There is thereby no chance for the blade to become unlocked while the handle is firmly gripped. The knife 60 shown in FIG. 7 has a safety 62 that is in the form of a button 64 that is captured in and slides in a slit 66 between the safety and releasing positions. This embodiment has the advantage of being readily operated with a simple movement of a thumb or finger while the knife is being held, although there is more chance that the position of the safety may be changed inadvertently. A final embodiment of a knife 70 with a safety 72 made according to the invention is shown in FIG. 8. This safety is in the form of a disk or washer 74 that pivots about a hinge pin 76 between a blade 78 and liner, not shown. Washer 74 pivots coaxially with but independently from the blade. An exposed textured perimeter region of the washer forms a contact surface 74a for manipulating the rotational position of the washer. A stud 80 is mounted on the washer as shown. Rotation of the washer by a thumb or finger moves the stud between safety and release positions, similar to movement of the stud in the embodiment of FIG. 7. This embodiment has the simplicity of using the knife hinge pin to provide the operating structure for movement of the stud. It is therefore seen that a safety made according to the invention provides means for preventing unlocking of a blade lock. Different embodiments provide different benefits, such as ease of use, ease of manufacture, and secure functioning of the safety by the gripping of the knife handle. Such a safety can be provided for a knife having a blade lock that moves between locking and unlocked positions. Movement of the stud or blocking element in the safety may be provided by various means, such as a pivoting or sliding arm or rotating disk. A lever action could also be provided. The stud, carrier and contact surface can all be part of a single element or be different parts joined or coupled together using mechanical means. Thus, although the present invention has been described in detail with reference to particular preferred embodiments, persons possessing ordinary skill in the art to which this invention pertains will appreciate that various modifications and enhancements may be made without departing from the scope of the claims. The above disclosure is thus provided for purposes of illustration and is not limitation.

Claims: A knife (10) comprising: a handle (18); a blade (12) mounted for pivoting relative to the handle (18) about a first axis (16) between a closed position and an open position; a leaf-spring (24a) having a lock element (24b) biased against the blade (12) when the blade (12) is in the closed position, for moving to a lock position in line with the blade(12) when the blade (12) is opened for preventing pivoting of the blade (12) from the open position toward the closed position, the lock element (24b) being movable between the lock position in which the blade (12) in the open position is prevented from pivoting and an unlock position in which the blade (12) in the open position is allowed to pivot characterized by the knife further comprising a safety (30) comprising: a stud (32); means (34) mounting the stud (32) relative to the handle (18) for movement relative to the lock element (24b) between a safety position in which the stud (32) prevents movement of the lock element (24b) from the lock position, and a release position in which the stud (32) allows movement of the lock element (24b) from the lock position; and manipulation means (34a) coupled to the mounting means (34) in a position exposed for manual contact by a person for moving the stud (32) between the safety position and the release position. A knife (10) according to claim 1 wherein the mounting means (34) comprises a member (34) mounted for pivoting relative to the lock element (24b) about a second axis (36) and the stud (32) is mounted on the member (34) spaced from the second axis. A knife (10) according to claim 2 wherein the member (34) is mounted to the handle (18). A knife (70) according to claim 2 wherein the second axis is coaxial with the first axis. A knife (70) according to claim 4 further comprising an axle (76) defining the first and second axes. A knife (50) according to claim 2 wherein the manipulation means (54) is spaced from the handle (18) when the safety (52) is in the release position and the manipulation means (54) is movable toward the handle (18) for moving the stud (32) toward the safety position, whereby a person gripping the handle (18) also holds the stud (32) in the safety position. A knife (50) according to claim 1 or 6 further comprising biasing means (56) for urging the stud (32) toward the release position. A knife according to claim 1 wherein the manipulation means (54) is positioned close to the handle (18) when the stud (32) is in the safety position and the manipulation means (54) is movable away from the handle (18) for moving the stud (32) toward the release position, whereby a person gripping the handle (18) also holds the stud (32) in the safety position.

Inventors: LAKE RONALD W, WALKER MICHAEL L, LAKE, RONALD W., WALKER, MICHAEL L.
Applicants: LAKE RONALD W, WALKER MICHAEL L, LAKE, RONALD W., WALKER, MICHAEL L.
Application year: 1996
Main classification: B26B1
IPC codes: B26B1