This invention relates to folding knives that rely upon a release button to lock the blade in either the open or closed position, or both, and to release the blade when it is locked to move it from one position to another. More specifically, the invention relates to an improved release button for such knives.
There are many types of knives, both automatic and manual, that utilize trigger-activated mechanisms that allow an implement to be moved between a folded position in which the implement is safely stowed in the tool handle, and an extended position in which the implement is ready for work. Of course, automatic versions of these knives include spring mechanisms that automatically drive the blade into the open position; manual knives require the blade to be moved manually from closed to open. The knife handle typically has two opposed handle portions defining a blade-receiving groove. A blade pivots on a shaft attached to the handle such that in a folded position the blade is stowed with the cutting portion of the blade safely in the groove, and such that in an extended position the blade is extended away from the handle, ready for use. The trigger mechanism controls movement of the blade from the closed to the open position—that is, when the blade is closed and the trigger is actuated, the blade may be moved either automatically or manually to the open position.
As noted, automatic opening knives include some kind of a spring-like or spring-driven mechanism that urges a blade from the closed position to the open position. In the closed position the blade must be locked against the constant opening force of the spring applied to the blade. Typical springs include spirally wound torsion springs that are wrapped around the pivot axis of the blade and which on one end engage the pivot pin, handle, liner or some other fixed, non-rotational structure, and on the other engage the blade. Other designs use compression springs and still others use extension springs and spiral wound flat springs and leaf springs. Many automatic opening mechanisms utilize or adapt the well-known sear type of design. Regardless of the particular mechanism used, when the locking mechanism is released, the spring forces the blade into the open position.
Preferably, push-button knives of the kinds described herein also include a locking mechanism that locks the blade in the open position. There are many designs for locking mechanisms to accomplish this task. Generally speaking, when the knife blade pivots into the open position, the blade's pivotal movement is stopped with a transverse blade stop pin housed in the handle. The locking mechanism is included to prevent the blade from pivoting back from the open into the closed position until the user purposefully closes the knife.
One common type of locking mechanism is a “liner lock.” This kind of mechanism relies upon a resilient lever formed as part of a handle liner. When the blade is pivoted to the open or extended position, the resilient lever engages a cooperatively formed ramp on the blade and thereby locks the blade in the open position.
Two separate patents describe different types of automatic knives that use push-button release mechanisms: U.S. Pat. No. 5,822,866 and U.S. Pat. No. 7,278,213. Both of these patents are described briefly below. Both are owned by the assignee of the present invention and both are incorporated herein by this reference.
The automatic opening knife detailed in the '866 patent relies on a push button bolt mechanism that includes a locking body that has a cylindrically tapered side wall portion. When the blade is extended to the open position, the tapered side wall portion of the locking body is urged by a compression spring into a locking position in which the locking body wedges between an engagement surface on the blade and a bore in the handle to lock the blade in the open position.
The locking mechanism for automatic knives disclosed in U.S. Pat. No. 7,278,213 also relies upon a push-button type of bolt. The trigger mechanism has a bolt that extends transverse to the handle. When an exposed portion of the trigger mechanism is depressed the bolt moves laterally in the knife handle. Once the bolt clears the tang of the blade, the blade disengages from the bolt and is swung to the open position by a spring.
The release buttons, also known as lock buttons, or “bolts” described in the two patents just mentioned are critical components of the knives since they control the opening mechanisms, and also lock the blade in both the open and closed positions. The bolts are defined by a trigger button end that is exposed to the outside of the handle, a tapered locking end at the opposite end, which is housed internally in the handle, and a central, axial and cylindrical shaft or shank interconnecting the two ends. When the button end is pushed, the bolt moves laterally in the handle. As the bolt moves, the tang of the blade, which is driven rotationally by a coil spring, has enough clearance to move past the bolt because the central shank is relatively small in diameter, thereby allowing adequate clearance and allowing the blade to rotate to the open position. Once the blade is in the open position, its rotation having been stopped by a stop pin, the pressure on the bolt is released and the tapered locking end of the bolt engages a portion of the tang, thereby locking the blade in the open position and preventing movement of the blade to the closed position.
The axial shank portion of the stop pins described in the patents just mentioned allows the pin to be oriented in an rotational position in the handle. In other words, the tang is able to swing past the shank of the pin regardless of whether the pin rotates about its long axis in the handle. However, this design inherently limits the configuration of the blade tang. Specifically, in order to provide enough clearance for the blade tang to clear the central shank of the bolt, the tang must be relatively short and make lock-up contact with the tapered locking portion of the bolt at a locking corner edge portion of the tang—if the tang were any longer, the tang would not be able to clear the axial central shank and the blade could not be opened or closed. Because the blade tang makes lock-up contact at a point on the bolt that is less than 50 percent of the distance across the bolt—that is, less than the axial centerline through the bolt, there is shearing force exerted on the trigger button.
There is a need therefore for an improved and more robust release button mechanism for use in a knife that relies upon a push button type of release and locking mechanism.
The present invention relates to an improved design for a release button or bolt for use in a push-button type release folding knife, in which the button serves to control the locking/opening mechanism, and to lock the blade in either the open or closed positions, or both positions.
The invention will be better understood and its numerous objects and advantages will be apparent by reference to the following detailed description of the invention when taken in conjunction with the following drawings.
The present invention relates to a release button for use in both automatic and manual folding knives. The release button functions as a lock button, since it locks the blade in both the open and closed positions. And while the release button described herein may be utilized in both manual and automatic folding knives, it is described and illustrated in the context of an automatic opening knife. Those of ordinary skill in the art will readily understand that the same release button described herein and shown in the drawings in an automatic knife may be used interchangeably in a manual knife. It will further be understood that in a manual knife the release button often is used to lock the blade only in the open position, rather than using the button to lock the blade in both the open and closed positions.
A preferred embodiment of an automatic opening knife 10 incorporating a release button in accordance with the illustrated invention is shown in the figures. Although the invention is described with respect to a particular style of knife, it will be appreciated that references to this style of a knife, and indeed this particular mechanisms for an automatic knife, are for illustrative purposes to describe the invention. Those of ordinary skill in the art will appreciate that the invention claimed herein is not limited to knives, but instead extends to any hand tool having the features claimed herein.
With reference to
The knife 10 shown in the figures includes an automatic opening mechanism similar to the types described in the two U.S. patents mentioned above, namely, U.S. Pat. Nos. 5,822,866 and 7,278,213. Preferably, an automatic opening knife 10 of the type shown in the figures includes a safety mechanism that prevents unintentional activation of the automatic opener mechanism. Although a safety mechanism is not shown in
With reference now to
The automatic opening mechanism used in knife 10 is actuated with a trigger mechanism, generally referenced herein with number 34. Trigger mechanism 34 includes a bolt 36—sometimes also called a release pin or release button, that is spring-loaded and extends in a transverse direction between handle halves 16 and 18, parallel to shaft 24. The bolt 36 is shown in isolation in
The first structural feature of bolt 36 is a button end 38 that is at the proximate end of the bolts and which is exposed out of handle half 16 in the assembled knife (
The second structural feature of bolt 36 is the end of the bolt opposite of button end 38, on the distal end of the bolt, which defines a locking body 42. Locking body 42 has a large diameter portion 44. Immediately adjacent the larger diameter portion is a tapered sidewall portion 46. The diameter of tapered sidewall portion 46 decreases gradually from the relatively larger diameter portion to an edge portion 58. Locking body 42 has a hollow base 48.
The third structural feature of bolt 36 is an off-center shank 50 that interconnects button end 38 to locking body 42. The off-center shank 50 is defined by a cylindrical outer wall portion 52 that extends partially around the perimeter of the bolt 36 and a flattened central portion 54 that extends across the bolt transversely to the longitudinal axis through the bolt. The outer wall portion 52 follows the same outer periphery as the outer peripheral wall of button end 38, and also the outer peripheral dimension of tapered sidewall portion 46 measured the “upper” limit of the tapered sidewall portion—that is, at edge portion 58. As shown in
Bolt 36 is preferably fabricated from a strong metal so it can withstand the rigors of repeated use, and preferably is monolithic. The bolt may be formed in any appropriate manner, for example by machining, molding or casting.
With returning reference to
A spacer 70 is positioned between handle halves 16 and 18 at the rearward end of handle 12 to maintain the handles in a spaced-apart relationship, and the handle halves are attached to one another with a variety of fasteners such as screws 72 that extend through bores in handle half 16 and thread into threaded bosses 74 on handle half 18. A blade stop pin 60 (which preferably is of the type described in U.S. Pat. No. 7,278,213) extends parallel to pivot shaft 24 and has its opposite ends fixed in the handle halves 16 and 18, respectively, with for example a screw 61. When the blade 14 is in the open position shown in
As best shown in
It will be appreciated that the position of the flattened portion 41 and the corresponding flattened portion of the bore 43 similarly maintain the position of the flat central portion 54 of shank 50. As detailed below, this maintains the bolt in the correct rotational position at all times, which allows the trigger mechanism 34 to operate. It will further be appreciated that there are numerous equivalent structures and mechanisms that could be used to fix the rotational position of bolt 36 relative to handle 12. For example, the flattened portion 41 of flange 40 could be replaced with a key on button 38 and a corresponding keyway formed in the handle. Alternately, a key and keyway could be formed on the locking portion 42, or relative rotation between the bolt and handle may be prevented by flattening facing surfaces of the locking portion 42 and cavity 45. These are just a few examples of structures that will serve the function of preventing relative rotation between the bolt and the knife handle. Those of ordinary skill in the art will recognize the many equivalent alternative structures available to define means for fixing the rotational position of the bolt relative to the handle, and for preventing rotation of the bolt in the handle.
The tang 80 of blade 14 will now be described in detail with particular reference to
Operation of the automatic opening is now described.
When blade 14 is in the closed position shown in
Operation of trigger mechanism 34 to allow blade 14 to rotate to the open position (arrow A in
Turning to
With reference once again to
By structuring shank 50 as described above, and specifically the manner of making the shank off-set so that the body of the shank does not extend more than 50 percent across the width of bolt 36 at edge 58, makes for a very strong bolt, and allows the length of tang 80 at flattened face 92 to be substantially longer than the tang used in prior art push-button release mechanisms where the shank of the bolt is axially aligned in the bolt. The bolt is stronger because there is more material that defines shank 50. The length of tang 80 at face 92 can be longer because with the geometric configuration of the shank 50, where flattened face portion 54 is less than 50 percent of the distance across the bolt, the longer tang is able to swing past the shank without making contact with it. Because the flattened face 92 defines the contact point with tapered portion 46, there is compressive force applied to the bolt and not a shearing force. The combination of these features produces a far sturdier release pin that is far less prone to failure.
It will be appreciated based on the description above and the drawings that release bolt 36 is movable between two separate positions. The first position is a locking position in which a portion of bolt 36, namely locking portion 42, lies in the space 20 between handle halves 16 and 18 and interacts with the tang 80 of blade 14. The bolt is thus in the first or locking position when the blade is locked closed, and when the blade is locked open. The second position is a release position in which shank 50 lies in space 20 and therefore defines a passageway 59 through which the tang may rotate. The bolt is in the release position whenever the button end 38 is pushed inwardly so that the blade may be automatically rotated from closed to open, and manually rotated from open to closed.
It will further be appreciated that certain modifications may be made to the bolt 36 without changing the principals of the invention. For example, although bolt 36 is illustrated as being cylindrical, the bolt could be of many other different geometric configurations. As another example, the bolt 36 is shown as being retained in the handle 12 by virtue of flange 40. However, there are many equivalent structures that may be used to retain the bolt in the handle. As yet another example of an equivalent structure, in the description above the shank portion 50 of bolt 36 does not extend past the axis through the bolt. However, the shank may be fabricated such that it approaches or even occupies the centerline through the bolt, but in that case the configuration of the tang 80 would need to be modified.
While the present invention has been described in terms of a preferred embodiment, it will be appreciated by one of ordinary skill that the spirit and scope of the invention is not limited to those embodiments, but extend to the various modifications and equivalents as defined in the appended claims.