External spring-loaded folding knife mechanism

Abstract

Opening and closing mechanism for folding knives with the blade returned by an external spring and easy release. The present invention relates to a mechanism for a folding knife with an external spring-loaded mechanism allowing partial locking of the blade in the open position, an intermediate closed position, and release by simple pressure from the user on the back of the blade. When the knife blade is opened, a hole (1) in the external spring allows the end of the spring to engage in a main notch (2) in the blade's tang. The angle of inclination (α) of the notch (2) allows the blade to be released by simple pressure from the user on the back of the blade. Figure for the abstract: FIGURE 6.

Description

Title of invention: External spring folding knife mechanism

[0001] There are different mechanisms of folding knives with external springs (called “fins” with the use of a stamped sheet metal serving as a spring).

[0002] The majority of folding knives with external palm spring have mechanisms with total locking of the blade in the open position (called "stop notch").

[0003] The main known external spring folding knife systems with a stop lock are described below: • The “Cra-cra” type knife, which is a knife with an external spring and a stop catch, the blade of which is released by pulling a ring attached to the external spring. The presence of this ring can be annoying when using the knife. • The so-called "palanquille" knife, which is a knife with a small lever attached to the spring that allows the blade to be unlocked by pressing on the blade to lift the spring. Closing the blade is therefore complex because you have to operate the lever while pressing on the back of the blade to be able to close the knife. • The “de ventana” type knife (used in Spain and Italy) which is an external spring knife where the locking catch is released by manually pulling the spring. The disadvantage of this system is that it requires a certain amount of finger strength to pull the spring and release the blade.

[0004] All these systems mentioned above have the advantage of a "stop" locking of the knife in the open position but have the disadvantage of unlocking the blade requiring a specific action from the user which is more or less complex and often impractical.

[0005] There are also external spring mechanisms with partial locking of the blade allowing for a “forced notch” or “flat notch” type operation.

[0006] These systems are described, among others, in PRADEL patent No. 411,954 published on June 30, 1910 (palm-type knife spring). These systems are manufactured by attaching a metal part to the palm spring which allows the external spring knife to reproduce the characteristics of a “flat notch” or “forced notch” mechanism. The disadvantages of these systems are as follows: • These systems require more complex manufacturing because a part must be attached by welding or riveting to the external spring. • Attaching a part to the spring creates a weak area in the knife mechanism.

[0007] The present invention relates to a mechanism for a folding knife with an external palm spring ([Fig. 1]) allowing partial locking of the blade in the open position, an intermediate closed position as well as unlocking by simple pressure by the user on the back of the blade.

[0008] This mechanism works with a hole (1) in the external palm spring ([Fig.l]) and two notches in the heel of the blade ([Fig.2]): a main notch (2) and an intermediate notch (3). When opening the knife blade, the hole (1) in the spring allows the end of the spring (5) to engage in the main notch (2) of the blade.

[0009] The geometry of the blade with its two notches on its heel combined with the hole in the spring allows the following advantages: • partial blocking of the blade in the open position (see [Fig.2]), • unlocking the blade by simply pressing on the back of the blade: under the effect of the force exerted by the user on the back of the blade, the blade presses on the spring by pivoting around its axis (4) and allows unlocking (see [Fig.3]). • a safety position when closing because when you press on the back of the blade to close the knife, initially the blade folds back approximately 45 degrees to rest on the intermediate notch (3) (see [Fig.4]). • a return force in the folded position of the knife: the spring (5) presses on the heel of the blade to keep the blade folded and prevent the knife from opening accidentally (see [Fig.5]).

[0010] Below is a brief presentation of the various figures attached to the description of the invention:

[0011] [Fig.l] represents the top and side views of the knife.

[0012] [Fig.2] represents the sectional view AA of the knife in the open position allowing see the mechanism with the spring engaged in the notch (2) of the heel of the blade.

[0013] [Fig.2a] shows the detail of the sectional view of the knife in the open position allowing to see the detail of the mechanism with the spring (5) engaged in the notch (2) of the heel of the blade, the points of contact between the spring (5) and the heel of the blade as well as how the angle alpha (a) of the notch (2) is defined allowing the blade to be released.

[0014] [Fig.3] represents the sectional view of the knife allowing to see the spring (5) lift and release the blade when the user presses the back of the blade.

[0015] [Fig.4] represents the sectional view of the knife allowing the blade to be seen folded by approximately 45 degrees when the spring (5) is wedged into the intermediate notch (3), the blade thus being semi-locked in this intermediate position.

[0016] [Fig.5] represents the sectional view of the knife allowing the blade to be seen in its closed position, the spring (5) exerting a force on the heel of the blade which is thus kept closed in the handle.

[0017] [Fig.6] figure for the abstract.

[0018] This mechanism is very simple to manufacture because there are no additional parts to the spring and the blade necessary for its operation (there is no lever or blade, no ring, and no part added to the spring by welding or riveting).

[0019] The external palm spring can be manufactured by stamping before heat treatment of a steel sheet, which must, once shaped, undergo heat treatment to obtain the sufficient level of hardness while ensuring flexibility allowing its spring action.

[0020] The handle of the knife can be made of wood or any other material.

[0021] The particular geometry of the blade heel (visible in [Fig.2a]) is explained as follows: in order for the blade to be unlocked by simple pressure from the user on its back, the blade heel must have the following particular geometry: the main notch (2) in the blade heel must have on one of its faces a slope forming an angle Alpha (a) with the theoretical line which connects the axis of the blade to the point of contact (Z) between the spring and the blade. This angle Alpha (a) must be greater than 30 degrees to allow, when a force is exerted on the back of the blade in the open position to fold it, to raise the spring (5) and thus unlock the blade which can then be folded into the handle of the knife.

[0022] The level of firmness or force to be exerted by the user to be able to fold the knife can be chosen during manufacture by adjusting this angle Alpha (a) of the main notch (2) on the heel of the blade between 30 degrees and 45 degrees to obtain a more or less firm closing mechanism (respectively very firm with an angle Alpha (a) of 30 degrees and flexible with an angle Alpha (a) of 45 degrees).

[0023] This closing system can be used for folding knives of all sizes but also for a closing system for any other object (corkscrew, fork or spoon).

Claims

Claims

1. Folding knife blade locking mechanism with external spring called "palm" allowing the blade to be unlocked by simple pressure from the user on the back of this blade, characterized in that the palm spring has a hole (1) and in that the heel of the blade has a main notch (2), allowing the blade of the knife, by unfolding by rotation around its axis (4), to come to lock in the open position when the end of the spring having a hole engages in the main notch (2) of the heel of the blade, and allowing the blade of the knife to be unlocked by simple pressure from the user on the back of the blade.

2. Folding knife blade locking mechanism according to claim 1 characterized in that the level of firmness of the knife locking or the level of force to be exerted by the user to be able to fold the knife can be chosen during manufacture by modifying the geometry of the main notch (2) on the heel of the blade by adjusting the angle Alpha (a) formed by the slope of the main notch (2) with the theoretical line connecting the axis (4) of rotation of the blade to the point of contact (z) between the spring and the blade between 30 degrees and 45 degrees to obtain a more or less firm closing mechanism.

3. Folding knife blade locking mechanism according to claims 1 and 2 above characterized by the creation of an intermediate notch (3) on the heel of the blade having the effect of creating an intermediate position when the user folds the blade of the knife and thereby ensuring safety when closing the blade of the knife.

4. Folding knife blade locking mechanism according to claim 1, characterized in that the external spring of the knife which when manufactured by stamping before heat treatment of a steel sheet must, once shaped, undergo heat treatment in order to guarantee the sufficient level of hardness while ensuring flexibility allowing its spring function.

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