KNIFE WITH BLADE EXPANSION ACTIVATED BY A MOVABLE HANDLE

Description

technical field

[0001] The invention relates to the field of knives comprising a blade mounted to slide longitudinally in a knife body and extracted from a knife body longitudinally under the action of a handle movable in rotation around an axis relative to the knife body. Previous technique

[0002] A cutter-type knife is known from document FR2 552 008 A1. It has a rotating trigger and a push mechanism on an inclined ramp of a blade holder to extend the blade longitudinally from the front of the knife. This device does not allow for a significant blade extension stroke, as this is limited by the angle of the ramp and the travel of the handle.

[0003] US patents 4,713,885 B2, 6,813,833 B2, and 7,322,110 B2 describe knives with a longitudinal blade extension. A two-rod system, forming the two arms of a compass, pushes a blade holder apart, thus controlling the longitudinal extension of the blade via a pivoting handle. These devices multiply the blade's extension length relative to the handle's travel, thereby increasing the blade's range of motion. Technical problem

[0004] However, these known solutions do not allow for a blade extension range comparable to that obtained with a simple pusher mounted on the knife body and moving longitudinally to operate a blade holder. It is therefore desirable to be able to further increase the blade extension range. Description of the invention

[0005] In view of this situation, the present disclosure proposes a knife having a body extending along a longitudinal axis and containing a blade holder equipped with a blade, for which the blade holder is maneuverable along said longitudinal axis to extend the blade from the body on a front side of said body by means of a handle that is angularly maneuverable relative to the body of the knife and retract it under the action of a return spring, the knife comprising a connecting rod device, configured to transform an angular movement of the handle into a longitudinal movement of the blade holder, comprising at least four connecting rods articulated to each other and guided between the body of the knife and the handle so as to produce a multiplication of the extension stroke of the blade relative to the rotation of the handle.

[0006] The characteristics described in the following paragraphs correspond to embodiments that can be implemented independently of each other or in combination with each other:

[0007] According to one embodiment, a first articulation is made between a rear part of the body of the knife and a first end of a first connecting rod, a second articulation is made between a second end of the first connecting rod and a first end of a second connecting rod, a third articulation is made between a second end of the second connecting rod and a first end of a third connecting rod, a fourth articulation is made between a second end of the third connecting rod and a first end of a fourth connecting rod, wherein the second end of the fourth connecting rod is provided with a fifth articulation with the blade holder and wherein the second and fourth articulation are configured to slide against an inner face of the handle while the third articulation is configured to slide on a part of the body of the knife.

[0008] The body of the knife advantageously includes a base relative to which the blade holder slides and side walls between which the blade holder moves.

[0009] The third joint 61 may include bosses 62 which slide in first grooves 12 made in said lateral walls of the body of the knife, the first grooves constituting said part of the body of the knife on which the third joint slides.

[0010] Advantageously the first grooves can constitute first ramps inclined with respect to the longitudinal axis of the knife with a slope of increasing inclination from the back to the front of the knife with respect to the longitudinal axis of the knife.

[0011] The fifth articulation may include internal pins received in second grooves on the blade holder, transverse to said longitudinal axis and parallel to said lateral walls.

[0012] The fifth joint may also include external pins which slide in third grooves made in the said lateral walls of the body of the knife, the said third grooves forming second ramps inclined with an increasing slope of inclination from the rear to the front of the knife relative to the longitudinal axis of the knife.

[0013] The third grooves can extend over the length of the blade's exit stroke.

[0014] According to a particular embodiment, the inclination of the first ramps is more pronounced than the inclination of the second ramps.

[0015] The handle is advantageously articulated on the front of the knife body.

[0016] The blade's extension stroke is greater than 2 times the stroke of the handle element and preferably in the order of 2.5 to 3 times the stroke of the handle element.

[0017] According to a particular embodiment, the knife is provided with a device for retaining the blade in the blade holder comprising a lug mounted on a spring tab and a blade release device comprising a pusher having a rib bearing on a free end of said tab and positioned so as to allow the blade to be released from the blade holder by pushing on said free end producing a twist of said tab and a disengagement of the lug from a hole in the blade when the knife is in a blade exit position. Brief description of the drawings

[0018] Other features, details, and advantages of the invention will become apparent from the following detailed description of non-limiting embodiments and from the analysis of the accompanying drawings, in which: [ Fig. 1A], [Fig. 1B] show an example of a knife according to this disclosure in perspective, respectively with the blade retracted and the blade extended; Fig. 2 ] shows an exploded view of the knife as described in this disclosure; Fig. 3 ] shows a view of the inside of a knife according to this disclosure; ] Fig. 4 ] shows a detail of a safety locking device on a handle; ] Fig. 5 ] shows a detail of a blade holder with blade locking. Description of the implementation methods

[0019] The drawings and description below contain elements that can not only help to better understand the present invention, but also contribute to its definition, if necessary.

[0020] Reference is now being made to Figures 1A and 1B which represent a knife according to the invention with the blade retracted Figure 1A and blade out figure 1BThe knife comprises a body 1, a pivoting handle 4 articulated on trunnions 15 on a front portion of the knife, and a blade 3 that extends and retracts along a longitudinal axis A of the knife from the front 1a of the knife. To extend the blade, an operator presses the pivoting handle 4, which can be angled relative to the body of the knife, against the body 1, thereby extending the blade by means of the mechanism described in particular in figures 2 and 3 .

[0021] According to the figure 3 in particular, the body1 extending along the longitudinal axis A and containing a blade holder 2 equipped with the blade 3 and maneuverable along said longitudinal axis to remove the blade from the body on the front side 1a of said body by means of the handle 4.

[0022] The blade holder slides on a base 1c of the knife and between lateral walls 1d, 1e of the blade holder parallel to a plane of the blade holder.

[0023] To do this, the knife includes a connecting rod device, between the handle and the blade holder, this connecting rod device being configured to transform an angular movement of the handle 4 into a longitudinal movement of the blade holder (2).

[0024] In the example shown, the connecting rod mechanism comprises four connecting rods 5, 6, 7, and 8, articulated to one another and guided between the knife body 1 and the handle 4, thus producing a gear ratio between the blade's extension stroke and the handle's rotation. This number of four connecting rods represents a compromise between the desired gear ratio, the complexity of the mechanism, and the difficulty of pressing the handle due to friction between the various components of the mechanism.

[0025] To retract the blade, the operator releases the handle and the blade holder retracts into the body of the knife 1 under the action of a return spring 10.

[0026] The connecting rod device, represented more particularly in figures 2 and 3 is such that a first articulation 51 is made between a rear part 1b of the knife body and a first end of a first connecting rod 5. To do this as shown in figure 2 , the rear of the knife body has 14 housings for the first 53 pins of said first articulation.

[0027] A second joint 52 is made between a second end of the first connecting rod 5 and a first end of a second connecting rod 6 and a third joint 61 is made between a second end of the second connecting rod 6 and a first end of a third connecting rod 7. This third joint has second pins from the second connecting rod and turned towards the inside of the knife to fit into housings in the third connecting rod and is configured to slide on a part of the body of the knife.

[0028] According to the example, this third joint further comprises bosses 62 which slide in first grooves 12 formed in the said lateral walls 1d, 1e of the knife body. A configuration in which the third joint slides against the bottom of the knife would be possible within the scope of this disclosure but would be less efficient because, according to the embodiment shown, the first grooves 12 constituting said part of the knife body on which the third joint slides form first ramps inclined with respect to the longitudinal axis A of the knife with a slope increasing from the rear to the front of the knife with respect to the longitudinal axis of the knife, which improves the progressiveness of the joint's movement and makes the effort required to press the handle more consistent than if the joint were guided parallel to the longitudinal axis.

[0029] Still referring to figures 2 and 3 , a fourth joint 71 is made between a second end of the third connecting rod 7 and a first end of a fourth connecting rod 8 and the second end of the fourth connecting rod 8 is provided with a fifth joint 81 with the blade holder.

[0030] Particularly represented in figure 3 , while the third joint 61 is configured to slide on a part of the knife body, the second and fourth joints 52, 71 are configured to slide against an inner face 4a of the handle 4 when the operator presses on the handle 4.

[0031] The connecting rod mechanism also includes a fifth joint 81 linking the fourth connecting rod 8 and the blade holder. To achieve this, a second end of the fourth connecting rod has third pins, also called internal pins 82, which are received in recesses in the blade holder. These recesses are formed by second grooves 21 on the blade holder, transverse to the longitudinal axis and parallel to the lateral walls 1d, 1e, which allows the fifth joint to move up into the knife during the extension of the connecting rod mechanism while the handle is pressed.

[0032] To improve the smooth movement of this joint, it includes fourth pins, also called external pins 83, which slide in third grooves 13 formed in the lateral walls of the knife body. These third grooves 13 form second ramps inclined with an increasing slope from the rear to the front of the knife relative to its longitudinal axis A. The third grooves 13 extend over the length of the blade's extension stroke, and the curvature of the ramps corresponds to the stroke of the internal pins 82 in the grooves 21 of the blade holder.

[0033] According to the example, the inclination of the first ramps 12 is more pronounced than the inclination of the second ramps 13 and the stroke of the first ramps 12 is shorter than the stroke of the second ramps 13.

[0034] Knife according to any one of the preceding claims wherein the blade extension stroke is greater than 2 times the stroke of the handle element and preferably in the order of 2.5 to 3 times the stroke of the handle element.

[0035] The knife as depicted in figure 2 includes for attaching the return spring 10, a tenon 22 on the blade holder and a tenon 92 on an attached rear cover which is fixed to the body by means of a groove 16, tongue 91 device, the tongues being inserted by force between the lateral walls 1d, 1e of the knife body.

[0036] According to the figure 5A lock can secure the handle in a position away from the body, i.e., in the retracted blade position. The lock is in the form of a latch 41 that moves laterally to release or lock the handle's movement relative to the rear cover by cooperating with a groove having a vertical portion 92 in which the latch can slide and a stop portion 93 in which the latch 41 can lock when the handle is released and the latch is pushed laterally.

[0037] According to the figure 5The knife includes a blade retention device in the blade holder comprising a lug 24 which fits into a hole 31 in the blade 3. The lug, which may be in the form of a trunnion with an upper face at least partially inclined, is mounted on a spring tab 23. The tab has a free end 26 directed towards the bottom of the body 1 and a blade release device comprising a pusher 11 provided with a rib 26 is positioned on the body of the knife so as to allow the blade to be released from the blade holder by pushing on said free end 26 which produces a torsion of the tab 23 and a disengagement of the lug 24 from the hole 31 in the blade, when the knife is in a blade extension position. Industrial application

[0038] The invention may be applicable in particular to knives known by the English name "cutter".

[0039] The invention is not limited to the examples described above, which are only by way of example, but encompasses all the variants that a person skilled in the art may consider within the framework of the protection sought.

Claims

1. Knife featuring a body (1) that extends along a longitudinal axis (A) and houses a blade holder (2) fitted with a blade (3), wherein the blade holder is movable along said longitudinal axis to extend the blade from the body at a front side (1a) of said body using a handle (4) that can be angularly manoeuvred relative to the knife body, and retract it under the action of a return spring (10), characterised in that it has a linkage mechanism designed to convert an angular movement of the handle (4) into longitudinal movement of the blade holder (2), having at least four connecting rods (5, 6, 7, 8) that are articulated to one another and guided between the knife body and the handle so as to produce a multiplication of the extension travel of the blade relative to the rotation of the handle.

2. Knife according to Claim 1, wherein the knife body has a base (1c) against which the blade holder (2) slides, and side walls (1d, 1e) that are parallel to a plane of the blade holder, between which the blade holder moves.

3. Knife according to Claim 1 or 2, wherein a first joint (51) is formed between a rear portion (1b) of the knife body and a first end of a first connecting rod (5), a second joint (52) is formed between a second end of the first connecting rod (5) and a first end of a second connecting rod (6), a third joint (61) is formed between a second end of the second connecting rod (6) and a first end of a third connecting rod (7), a fourth joint (71) is formed between a second end of the third connecting rod and a first end of a fourth connecting rod (8), wherein the second end of the fourth connecting rod (8) is equipped with a fifth joint (81) with the blade holder, and wherein the second and fourth joints (52, 71) are configured to slide in contact against an inner face (4a) of the handle (4), while the third joint (61) is configured to slide along a portion of the knife body.

4. Knife according to Claim 3, wherein the third joint (61) has bosses (62) that slide in first grooves (12) formed in said side walls (1d, 1e) of the knife body, the first grooves (12) constituting said part of the knife body on which the third joint slides and forming first ramps inclined relative to the longitudinal axis (A) of the knife with an increasing slope from the back to the front of the knife relative to the longitudinal axis of the knife.

5. Knife according to Claim 3 or 4, wherein the fifth joint (81) has internal pins (82) received in second grooves (21) on the blade holder, transverse to said longitudinal axis and parallel to said side walls (1d, 1e), and has external pins (83) which slide in third grooves (13) made in said side walls of the knife body, said third grooves (13) forming second ramps inclined with an increasing slope from the rear to the front of the knife with respect to the longitudinal axis (A) of the knife.

6. Knife according to Claim 5, wherein the third grooves (13) extend over a length of the blade extension travel.

7. Knife according to Claims 4 and 5, wherein the inclination of the first ramps is more pronounced than the inclination of the second ramps.

8. Knife according to any one of the preceding claims, wherein the handle (4) is hinged to the front of the knife body.

9. Knife according to any one of the preceding claims, wherein the extension travel of the blade is greater than twice the travel of the handle element, and preferably between 2.5 and 3 times the travel of the handle element.

10. Knife according to any one of the preceding claims having a device for securing the blade in the blade holder having a lug (24) mounted on a spring tab (23) and a device for releasing the blade having a pusher (11) equipped with a rib (25) resting on a free end (26) of said tab (23) and positioned so as to allow the blade to be released from the blade holder by pressing on said free end (26), thereby causing said tab (23) to twist and disengaging the lug from a hole (31) in the blade when the knife is in the blade-extended position.