EP0353174B1 - Takedown archery bow showing a particular vibratory behaviour - Google Patents

Abstract

Take-down archery bow showing an improved vibratory behaviour. <??>This bow comprising in combination: A. a bow body obtained by moulding and having a main part (1), the general axis of which is rectilinear, terminating on each side in a plate reinforced by ribs, each extended by a end (2, 3) of approximately parallelepipedic form, inclined relative to the main part; B. two semi-rigid interlocking sleeves (10, 11) force-fitted onto the two ends of the bow body and having the form of a widened parallelepiped; C. two flexible branches (8, 9), the ends of which have a parallelepidedic form matched to that of the ends of the body, so that they can likewise be interlocked in the fastening sleeves; D. a device (38) for immobilising one end of each flexible branch; E. mounted in a perforation made in the aperture of the bow body, a spacer system (21) of a new type allowing the position of the arrow to be adjusted both horizontally and vertically. <IMAGE>

Description

The present invention relates to a removable competition arch with improved vibratory behavior.

Archery has experienced significant development in recent years, and the high-performance equipment designed to meet the expectations has improved considerably.

Thus, for the past ten years, all bows have had the same conformation and the same general characteristics linked to the specific functional conditions of competitive archery. For practical reasons, they are most often removable, formed by a bow body and two flexible end branches fixed removably on the body of the bow, intended to tension the rope.

The branches constitute the flexible parts of the bow which store the potential energy during the tensioning of the rope. In the removable arches, they have at one of their ends a fixing heel making it possible to mount them on the body of the arch. At the other end, these branches include a headstock and a groove intended for the placement of the rope.

• . la fenêtre où viennent se fixer les accessoires de visée et de support de flèche, en particulier le système écarteur permettant d'écarter plus ou moins la flèche du corps d'arc ;
• . la poignée permettant la saisie et la tenue de l'arc ;
• . les logements des branches qui permettent leur fixation, cette fixation s'opérant le plus souvent au moyen d'un système de vissage.

The arch body, which constitutes its central part, has three main elements, namely:

• . the window where the aiming and arrow support accessories are fixed, in particular the spacer system making it possible to more or less separate the arrow from the bow body;
• . the handle for gripping and holding the bow;
• . the housings of the branches which allow their fixing, this fixing taking place most often by means of a screwing system.

In addition to these main elements, there are many additional elements, including stabilizers made of a barrel of variable length on which a counterweight of variable weight can slide, shaft which is screwed onto the body of the arch via a linkage damper. These stabilizers have the function of balancing the arc and partially absorbing vibrations.

The vibratory behavior of the arc proves to be complex and a source of drawbacks which can become major. Indeed, the vibrations generated by the release propagate in the various elements of the arc and are transmitted in a harmful way to the wrist of the user. They affect the accuracy of the shot and offset the arc at the end of the shot in a sometimes uncontrollable way.

The stabilizers commonly used cannot constitute a satisfactory solution because of their low efficiency in neutralizing vibrations.

It has been imagined to conform to the ends of the arch body of the recessed housings into which the ends of the branches are inserted, the connection being provided with a locking-snapping system, see US Pat. No. 4,574,766 serving as a base for the preamble of claim 1.

Another difficulty lies in the nature and the reduced possibilities of the spreader system intended to adjust the position of the arrow before firing. Indeed, known spacer systems generally allow only one adjustment in the position of the arrow, which can only be more or less spaced from the arch body, but whose position cannot be changed in height.

Separator systems are also known which can be adjusted vertically, but not horizontally or transversely (patent FR 2 580 795).

Finally, the use of carbide fibers is known for the manufacture of arcs, but only in lamellar form over the entire length of the arc in order to seek flexibility and not on an intermediate junction piece for the purpose of rigidity (US patent 3,850,156).

The present invention aims to remedy all these drawbacks by proposing a removable competition arc with improved vibratory behavior compared to that of known arcs and which also comprises a spacer system allowing better adjustment of the boom.

The present invention thus relates to a removable competition arch according to claim 1.

It has also been imagined to make the receiving cavities for the ends of the branches with cover pieces with folded edges, screwed or riveted to the ends of the arch body (patent FR 2 580 795) or to fix each branch on the body. of arc by means of a prismatic intermediate piece fixed on the end of the body of the arc, (US Patent 3,326,200)

In addition, there are certainly known different systems for immobilizing a plate inserted in a slot or a gutter, but, on the one hand their field of application is completely foreign to the manufacture of competition bows, and on the other hand , either they must be maintained by a continuous effort (GB patent 118 106), or they implement an intermediate clamping part (US patents 4,589,640 and GB 2,081,367).

Solutions of this type only slightly reduce the level of vibrations. The presence of screwed or riveted metal parts is also a source of additional vibrations.
We can for example refer to US Pat. No. 4,648,376.

The body of the arc according to the invention can be obtained by molding a metal alloy of the type used in aeronautics.

Its parallelepiped ends connected to the arch body by reinforcing ribs offer the advantage of having a mechanical connection with low torsion with a large mass which promotes the solidity and the dynamic and static stability of the arch at the same time as the vibration damping, eliminating the need for front stabilizers positioned at both ends of the arch body.

Maintaining each branch by embedding in a sleeve not using a technique using transverse fixing means, for example screwing, also promotes the damping of vibrations, as well as the absence of front stabilizers, the required perforations by the screw fixing systems of the branches and by the front stabilizers constituting vibration wells and causing concentrations of stresses which weaken the mechanical resistance of the arc while generating low frequency vibrations.

According to the invention, the semi-rigid receiving sleeves are made of carbon fibers and, more precisely, of a material obtained by weaving carbon threads. They have a thickness of a few millimeters and a length adapted to that of the parallelepipedic ends of the body of the arch.

The use of carbon fibers allows the production of sleeves which have qualities of lightness at the same time as an exceptional mechanical resistance, while also contributing to the damping of vibrations.

The ends of the arch body, as has already been said, are forced into the sleeves, which can be fixed thereon by gluing. The corresponding flexible branch is then inserted into the sleeve where it can be placed isostatically by means of six suitably arranged points of a wear-resistant material, such as that known under the name of teflon.

The nature of the material from which the sleeve is made, namely carbon fibers, gives it highly damping properties with respect to high frequency vibrations.

However, the static and dynamic balancing of the arc body, thanks to the massive ends, makes it possible to transform the low frequency vibrations of the natural modes of its elements into high frequency vibrations, which are strongly damped by the semi-rigid material in which are made the sleeves.

Due to its original design, the arch body according to the invention exhibits a vibratory behavior very clearly superior to that of existing arch bodies, making in particular unnecessary the presence of frontal stabilizers, positioned at the two ends of the arch body. bow. This also results in an appreciable gain both in terms of the weight of the arc as its cost price.

The damping of the vibrations of the arch body can be further improved by the installation, on its handle, of an orthopedic overgrip made of a material of the expanded foam type.

Such an over-grip can be formed by cold injection of a foam of a synthetic resin in a deformable envelope fixed by bonding to the handle of the bow.

The damping can be further improved by a holding-wedging device providing a pressure contact against the large flank of the insert end of each flexible branch.

The invention will be better understood on reading the detailed description which follows of an arc body according to the invention shown in the appended drawing, it being understood that this description has no limiting character with respect to the invention.

• . la figure 1 est une vue en perspective de trois quarts du corps d'un arc selon l'invention ;
• . la figure 2 est une vue en coupe longitudinale du système écarteur qui vient se loger dans le perçage représenté sur la figure 1 ;
• . la figure 3 est une vue schématique en perspective montrant un exemple de dispositif d'immobilisation et son implantation à l'extrémité du corps de l'arc ;
• . la figure 4 est une vue en coupe longitudinale de l'extrémité du corps de l'arc au niveau de l'encastrement des branches.

In the attached drawing,

• . Figure 1 is a perspective view of three quarters of the body of an arc according to the invention;
• . Figure 2 is a longitudinal sectional view of the spacer system which is housed in the bore shown in Figure 1;
• . Figure 3 is a schematic perspective view showing an example of an immobilizer and its location at the end of the body of the arc;
• . Figure 4 is a longitudinal sectional view of the end of the body of the arch at the level of the embedding of the branches.

In FIG. 1, it can be seen that the body of the arch comprises a main part 1 whose axis of general longitudinal direction is rectilinear, extended by two ends 2 and 3 of parallelepipedal shape inclined relative to the general direction of the part main 1 and each having a shoulder 4 and 5 on each of which can be supported heel of one of the ends 6 and 7 of a flexible arc branch 8 and 9 removable from the main part 1.

A mounting sleeve 10 or 11, also of parallelepiped shape, is fitted onto each of the two ends 2 or 3 of the arch body. It is forced into it, leaving a free space in the interior volume of each sleeve, forming a housing, of shape and dimensions corresponding to those of each end 6 or 7 of the corresponding flexible branch 8 or 9.

The ends 2 and 3 of the body of the arch are connected to the central part by a curvature of the material 12 and 13 doubled on the rear face by two reinforcing ribs 14, 15 and 16, 17 making it possible to improve the rigidity and the stability of the arc.

In the main part 1 of the arch body, there is formed a handle 18 surmounted by a window 19 in which a cylindrical bore 20 is provided for a spacer system 21.

Another hole 22 disposed immediately below the handle 18 is used for the establishment of a central stabilizer, not shown.

In FIG. 2, the spacer system 21 is shown, consisting of a hollow screw 23 mounted in the bore 20 formed in the arc body. This screw 23 is made integral with the arc body by means of a part of a nut 24 mounted at one end of the screw 23 and bearing against one of the cheeks 25 of the arc body in a cylindrical counterbore 26 machined to one end of the bore 20 and on the other hand a lock nut 27 associated with an adjustment head 28 mounted on the other end of the screw 23 and bearing against the other face of the arc body.

The adjustment head 28 consists of a nut 29 mounted on the screw 23 and bearing against the lock nut 27 and of a cylindrical piece 30, secured to the nut 29 by means of a screw 31 and coming fit into a recess 32 formed in the screw 23 and terminated by a bottom 33 and a bore 34. This cylindrical part 30 is used to compress a spring 35 housed in the recess 32 between the cylindrical part 30 and a press button 36 having a shoulder coming to rest against the bottom 33 of the screw 23.

The screwing of the nut 29 in the screw 23 causes the displacement of the part 30, which compresses the spring 35 and conversely, the unscrewing of the nut 29 causes the spring 35 to loosen. The press button 36 is formed from two cylinders of different diameters. The narrowest cylinder passes through the bore 34 and its attached head 37 serves as a support for the arrow.

By unscrewing the nut 24, the lock nut 27 and the adjustment head 28, it is possible to move the assembly in the bore 20 in order to modify the position of the press button 36 both vertically and laterally, as well as its spacing of the cheek of the arch body. Once the adjustment has been made, screwing the assembly together fixes the press button 36 at the chosen position.

In order to further improve the vibratory behavior of the arc and to compensate for the wear of the embedded ends of the flexible branches in the end sleeves, there is provided according to the present invention, a wedging-holding device.

It is for example a device 38 for immobilization by holding-chocking, using a cam 39, mounted integral with an axis 40 movable in rotation over a sufficient angular deflection amplitude making it possible to obtain good pressure tightening.

This device is conventionally mounted on one and the other of the transverse edges 41 of one and the other end 2 or 3 of the body of the arch each covered with a receiving sleeve 10 or 11 of a end 6 or 7 to be maintained with a flexible arc branch 8 or 9.

The axis 40 is carried by a receiving part, socket or the like, 41 secured to the body of the arc, or comes to rest in a tapped hole. Any other assembly is possible.

Thus, the cam pivots either around the axis 40, or with this axis.

It is maneuvered manually so that it can be easily disengaged by pivoting on each insertion or disengagement of the flexible branches.

The part 39 acting as a cam has a curvilinear profile 42 slightly curved over a part of its contour 43, so as to bear through an area 44 of larger surface, on one of the large flanks 45 facing the embedded end of each flexible branch 8 or 9.

This cam 39 is made of semi-hard synthetic material, for example nylon, polyamide or polyester, so as to take advantage of the slight elastic crushing of the material against the harder face of the flexible branch of the arch.

This takes up wear compensation and sufficient immobilization pressure so that the end of the branch forms a solid body with the sleeve, and thus neutralizes the parasitic vibrations that may remain.

According to another embodiment, the cam pivotally mounted relative to the body of the arc is operated using a key or any other tool coming to get caught in its head in order to pivot either the cam or its axis 40 which can be made integral with the cam.

The body of the cam preferably has a projection 46 situated opposite its zone of contact with the corresponding flexible branch in order to be able to maneuver it more easily by hand.

It may also include an elastic return in the pinch position.

The immobilization device according to the invention allows, thanks to the pressure contact, to obtain a mechanical clamping for the mechanical maintenance of the branches and the additional damping of the vibrations coming from the shooting.

It also ensures that the play is taken up due to mechanical wear at the end of the branch, which is successively fitted in and out at each firing sequence.

The ends of the arch body can in particular have a shape other than a parallelepiped, for example in the trunk of a pyramid, and the fixing sleeves have the corresponding suitable shape.

Claims (10)

1. Competition bow comprising firstly a bow body, the said bow body, which is produced by moulding, being provided with a handle (18) and comprising a principal portion (1) of which the neutral axis is rectilinear, and secondly two flexible branches (8, 9) which can be mounted such that they are immobilised on the ends of the said bow body, characterised:

   - in that the principal portion (1) of the bow body is extended on either side by a plate reinforced with ribs (14, 15 and 16, 17), the said plates terminating in ends (2, 3) which are approximately parallelepipedal, which are inclined relative to the principal portion (1), and which do not contain any other perforation;

   - in that semi-rigid embedding sleeves (10, 11) are force-mounted on the ends (2, 3) of the said bow body and have an embedding cavity in the form of a recessed parallelepiped;

   - in that one end (6, 7) of each flexible branch (8, 9) has a parallelepipedal shape adapted to the shape of the embedding cavity such that it can be embedded in the housing delimited by the sleeves (10, 11) and the ends (2, 3) of the said body; and

   - in that the bow further comprises a device (38) for immobilising each end (6, 7) of the flexible branches (8, 9) which can be embedded, and a spacer system (21) mounted in a drilling (20) provided in a slot (19) in the bow body, enabling the direction of the arrow to be adjusted horizontally and vertically.
2. Bow according to Claim 1, characterised in that the embedding sleeves (10, 11) are made of carbon fibres.
3. Bow according to Claim 2, characterised in that the embedding sleeves (10, 11) are made of a material obtained by the weaving of carbon threads.
4. Bow according to any one of the preceding claims, characterised in that its handle (18) is covered with an orthopaedic over-handle made of expanded foam.
5. Bow according to Claim 4, characterised in that the said orthopaedic over-handle is produced by injection of a synthetic resin foam in the cold state into a deformable casing secured by bonding on the bow handle.
6. Bow according to any one of the preceding claims, characterised in that the spacer system (21) consists of a hollow screw (23) which is mounted in the drilling (20), formed in the slot (19), and which is rendered integral with the body firstly by means of nut (24) which is mounted at one end of the screw (23) and which bears against one of the flanks (25) of the bow body in a cylindrical counter-sinking (26) machined at one end of the drilling (20), and secondly by means of a counter-nut (27) associated with an adjusting head (28) which is mounted at the other end of the screw (23) and which bears against the opposite face of the body, the adjusting head (28) consisting of a nut (29), which is mounted on the screw (23) and which bears against the counter-nut (27), and a cylindrical part (30) which is rendered integral with the nut (29) by means of a screw (31) and which fits into a recess (32) which is formed in the screw (23) and which terminates in a base (33) and a drilling (34), this cylindrical part (30) being used to compress a spring (35) which is also placed in the recess (32) between the cylindrical part (30) and a push-button (36) which is provided with a shoulder which bears against the base (33) of the screw (23).
7. Bow according to any one of the preceding claims, characterised in that its body is produced by the moulding of a metal alloy of the aeronautical type.
8. Bow according to any one of the preceding claims, characterised in that the device (38) for immobilising the embedding end (6, 7) of each branch (8, 9) is secured on the lateral edge (41) of each end (2, 3) of the bow body employing a pinching part which can move between a turned-down rest position and an operating position in which it exerts contact pressure against the adjacent flank of the embedding end of the corresponding branch.
9. Bow according to Claim 8, characterised in that the pinching part is a cam (39) which can rotate about a pin (40) perpendicular to the adjacent lateral edge of the bow body.
10. Bow according to Claim 9, characterised in that the cam (39) has a slightly curved contour (43) over at least part of its profile (42).

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