WO2024170981A1

WO2024170981A1 - Attachment device with decoupling and anti-ejection functions

Info

Publication number: WO2024170981A1
Application number: PCT/IB2024/050884
Authority: WO
Inventors: Fabien Tanty; Patrice Desplanches
Original assignee: Knds France
Priority date: 2023-02-13
Filing date: 2024-01-31
Publication date: 2024-08-22
Also published as: FR3145785A1

Abstract

The invention relates to an attachment device (1) for attaching an element to be attached to a support element of a structure, in particular to a wall of an armoured vehicle, which attachment device (1) comprises a body portion (4) capable of being rigidly attached to the support element and a head portion (5) capable of being rigidly attached to the element to be attached, the body portion (4) and the head portion (5) being coaxial, a fusible region (6), configured to break under a predetermined load, connecting the head portion (5) to the body portion (4), the device comprising retaining means (7, 9) which, in the event of rupture of the fusible region (6), are configured to render the body portion (4) and the head portion (5) inseparable and keep them in direct contact with each other.

Description

Fastening device with decoupling and anti-projection functions

The technical field of the invention is that of fixing devices allowing the fixing of an element to be fixed on a support element of a structure.

The fastening device according to the present invention is particularly suitable for military use, in particular for fastening equipment to an interior wall of an armored vehicle.

As is known, equipment inside an armoured vehicle is generally fixed to the interior wall of the vehicle by fixing devices comprising spacers or columns.

We know, for example, the French patent FR2670842, which describes a fixing device comprising a spacer tightened against the wall of a vehicle by a nut and a screw whose rod passes through the spacer and whose end cooperates with a tapped hole in the equipment to be fixed.

French patent FR2859451 is also known, which describes a fixing device for connecting two structural parts with a determined spacing, which device comprises a tubular spacer and a fixing member, such as a screw or a stud, passing through said spacer.

However, when an explosive device, such as a blast mine, is activated near the structure, such fastening devices transmit the entire stress received by the wall of the structure to the equipment fixed to this wall, leading to a risk of rupture of this equipment. In addition, the resulting shock on the wall of the structure is such that the elements of these fastening devices are likely to be sheared and therefore the equipment is violently projected inside the structure, thus constituting a vulnerable projectile.

To partially overcome these drawbacks, French patent FR3036145 proposes using a fixing appendage comprising two parts separated by a weakened zone calibrated to break. Thus, when a load exerted on the appendage exceeds the acceptable load level at the weakened zone, the appendage breaks. Such a breakage makes it possible to limit the transmission of the stress received by the structure to which the appendage is fixed.

In addition, this patent proposes to equip this appendix with a flexible link capable of retaining the part of the appendix likely to be projected in the event of rupture of the weakened zone. Thus, in the event of rupture of the weakened zone, the two parts of the appendix are held together and at a moderate distance from each other. Such a flexible link therefore makes it possible to prevent part of the appendix from being projected in the event of rupture of the weakened zone, which could injure a person located in the vicinity of the appendix or damage nearby equipment.

However, such a fixing device comprises several parts, in particular a flexible link that must be integrated inside the two parts of the body of the appendage, which makes it relatively complicated to produce. In addition, this flexible link does not allow the part of the appendage that cooperates with equipment to be held in position following the rupture of the weakened zone. As a result, the equipment becomes mobile relative to the wall and risks hitting a person or other equipment located near the wall, depending on the length of the flexible link.

It is therefore the aim of the present invention to propose a fixing device making it possible to provide a fixing function equivalent to a fixing by a column or spacer under normal mechanical constraints, making it possible to decouple the element to be fixed from the support element during an event such as a mine explosion without creating damage to the element to be fixed and to the surrounding parts, capable of retaining its fixing function following decoupling and capable of being produced in a simple manner.

Application WO 03/004958 A2 discloses a military vehicle in which a seat is fixed to a floor by means of a fixing device according to the preamble of claim 1.

The invention thus relates to a fixing device for fixing an element to be fixed to a support element of a structure, in particular to a wall of an armoured vehicle, which fixing device comprises a body part capable of being secured to said support element and a head part capable of being secured to the element to be fixed, the body part and the head part being coaxial, a fusible zone configured to break under a predetermined load connecting the head part to the body part, the fixing device comprising retaining means configured to, in the event of rupture of the fusible zone, make the body part and the head part inseparable and keep them in direct contact with each other, characterised in that the retaining means comprise a chamber-forming element secured to the body part and a piston-forming element secured to the head part, the chamber-forming element defining a cavity in the body part and comprising a radial wall which extends transversely relative to the axis of the body part and the head part, the radial wall comprising the fusible zone, the piston-forming element comprising a rod axial passing through the radial wall and a radial collar formed around the rod and received in the cavity, the chamber-forming element and the piston-forming element being configured such that in the event of rupture of the fusible zone, the rod is able to slide in the cavity and the collar is retained in the cavity by abutment against the radial wall.

Such a fixing device is capable of providing a function of holding an element to be fixed in position relative to a support element, a decoupling function between the element to be fixed and the support element thanks to the presence of a fusible zone, and an anti-projection function of the element to be fixed and of maintaining its position following decoupling thanks to the presence of the retaining means.

The decoupling function prevents, during an event such as a mine explosion, the full transmission of shock or impact energy to the element to be fixed via the fixing device.

The retaining means prevent the body part and the head part from becoming separated following decoupling, in other words preventing the head part from being thrown a certain distance from the body part. Thus, the anti-projection function prevents the element to be fixed from colliding with the environment of the fixing device following decoupling.

In particular, in the event of rupture of the fusible zone, the head part is held substantially coaxially with the body part, and its axial movement is limited by the radial wall of the chamber against which the collar is likely to come into abutment.

Preferably, the fusible zone comprises at least one reduced section calibrated at rupture.

The reduced section may be defined for example by at least one of the following means: notch, groove, slot, groove, groove or the like.

Advantageously, the chamber-forming element is an element defining a cylindrical cavity, the piston-forming element is a cylindrical element comprising a cylindrical rod and a cylindrical collar, and the fusible zone is an annular zone, the diameter of the annular zone being greater than the diameter of the rod and less than the diameter of the collar.

Preferably, the diameter of the rod is slightly smaller than the diameter of the annular zone and the diameter of the collar is slightly smaller than the diameter of the cavity. This allows better guidance of the movement of the piston element relative to the chamber element during a rupture of the fusible zone.

The chamber-forming member may include a plurality of vents configured to allow air to escape from the cavity.

Such vents, depending on their number, dimensions and positioning, make it possible to control the speed of movement of the piston element relative to the chamber element following decoupling between the head and body parts.

At least one mechanical element may be arranged inside the cavity so as to dampen the movement of the head portion relative to the body portion in the event of rupture of the fusible zone.

The presence of at least one such mechanical element therefore allows a progressive and slowed movement of the head part following its decoupling from the body part.

Preferably, the device comprises, at one of its axial ends, a first fixing zone secured to the body part, in particular a male zone, and, at the other of its axial ends, a second fixing zone secured to the head part, in particular a female zone, the first and second fixing zones being coaxial.

The first attachment area may be a male rod, with or without threads, and the second attachment area may be a female bore, with or without tapping.

Such securing means are removable securing means allowing disassembly of the element to be fixed with respect to the fixing device as well as disassembly of the fixing device with respect to the support element. In addition, the arrangement of these securing means makes it possible to support the element to be fixed at a distance from the support element, the fixing device being interposed between the element to be fixed and the support element.

The device can be made of plastic or metal.

Advantageously, the device is a single-piece part capable of being produced by 3D printing or by an additive manufacturing process.

This means that the fixing device can be produced quickly and easily. Such manufacturing techniques allow for a high degree of adaptation and even custom manufacturing.

The present invention will be better understood from the following description of a particular embodiment, a description made in light of the accompanying drawings, in which drawings:

shows in longitudinal section a fixing device according to the invention, fixed to a wall and carrying equipment;

represents in longitudinal section a fixing device according to the invention, in its configuration before rupture of the fusible zone;

shows in longitudinal section the fixing device of the , following the rupture of the fusible zone; and

is a perspective view of the fixing device of the following the breakup.

If we first refer to the , it can be seen that the fixing device 1 according to the present invention is intended to be used for fixing an element to be fixed 2, such as an armoured vehicle equipment, on a support element 3 of a structure, such as an internal wall of an armoured vehicle, the fixing device 1 then being interposed between the equipment 2 and the wall 3. In other words, in the mounted state, the fixing device 1 projects relative to the wall 3. The fixing device 1 is in the form of a longitudinal part extending along a longitudinal axis X which is intended to be orthogonal to the wall 3 to which the device 1 is fixed.

As can be seen in Figures 1 to 4, the fastening device 1 according to the present invention comprises a body part 4 and a head part 5 connected together by a fusible zone 6. Thus, the fastening device 1 is a monobloc part, i.e. in a single piece. This part can be made of any material suitable for the load support, preferably plastic or metal, the choice of material and dimensions of the part being functions of the constraints to which the part must resist. The part being monobloc without assembly or welding, it can be manufactured by 3D printing or by an additive manufacturing process.

The body part 4 is intended to be fixed directly to the wall 3, or to any other support element, and to come into direct contact with it. Generally speaking, the body part 4 comprises a chamber-forming element 7 and a first fixing zone 8.

In the embodiment shown, the chamber-forming element 7 is generally in the form of a tubular cylindrical body of revolution which extends along the longitudinal axis X. This body is closed at one of its axial ends by a circular bottom wall 70 whose diameter is equal to the diameter of the cylindrical side wall 71 of the body. The other axial end of the body comprises an annular radial wall 72 which extends radially towards the inside of the body. The radial wall 72 is parallel to the bottom wall 70 and is located opposite the latter. The radial wall 72 comprises a reduced section 6 calibrated at break in the vicinity of its junction zone with the head part 5, which reduced section 6 constitutes the fusible zone 6. This fusible zone 6 is an annular zone of diameter D1 less than the internal diameter D2 of the cylindrical side wall 71 and whose central axis is coaxial with the longitudinal axis X. The reduced section 6 can be formed by two circumferential grooves 60, 61, of the same center and the same diameter, made on the two faces of the radial wall 72.

It should be emphasized that the fusible zone 6 may be a zone of reduced thickness, a zone comprising at least one crack or any other fatigue zone capable of breaking under a predetermined load.

A peripheral annular wall 73 may be formed around the side wall 71 of the body, in the vicinity of the bottom wall 70, which wall 73 extends in a transverse plane of the body. The bottom wall 70, the side wall 71 and the radial wall 72 define a cylindrical cavity 74 in the chamber member 7.

Flats (not shown) may be provided on the cylindrical side wall 71 to serve as support surfaces for a wrench or a screwing tool, thereby facilitating the fixing of the device 1 to the wall 3.

In the embodiment shown, the first fixing zone 8 is integral with the external face of the bottom wall 70. This first fixing zone 8 is in the form of a male cylindrical rod 80 extending coaxially to the longitudinal axis X, an annular groove 81 being formed between the rod 80 and the bottom wall 70. This rod 80 may comprise an external thread capable of cooperating with a corresponding thread provided in a housing of the wall 3. Thus, in the mounted state, the male rod 80 is received in the housing of the wall 3, in particular by screwing, and the external face of the bottom wall 70 comes to bear against the wall 3.

The head part 5 is intended to receive and support the equipment 2 to be fixed to the wall 3. Generally, the head part 5 comprises a piston element 9 and a second fixing zone 10.

The piston-forming element 9 is generally in the form of an axial rod 90 provided with a radial collar 91. The rod 90 is a cylindrical rod of revolution extending along the longitudinal axis X and having a first axial end received in the cavity 74 and a second axial end arranged outside the cavity 74. Thus, the rod 90 passes through the radial wall 72 and is connected to the radial wall 72 over its entire circumference. In other words, the junction zone between the rod 90 and the radial wall 72 is an annular junction zone whose diameter is the diameter D3 of the rod 90. The diameter D3 of the rod 90 is therefore less than the diameter D1 of the fusible zone 6. The junction zone is located in the vicinity of the first axial end of the rod 90, which first end carries the collar 91.

The collar 91 is in the form of a disk projecting radially outwards relative to the cylindrical face of the rod 90. The diameter D4 of the collar 91 is therefore greater than the diameter D3 of the rod 90, less than the internal diameter D2 of the cylindrical side wall 71, and greater than the diameter D1 of the fusible zone 6. The collar 91 extends in a plane orthogonal to the longitudinal axis X and parallel to the plane of the radial wall 72.

In the embodiment shown in Figures 2 to 4, the axial rod 90 is a solid rod. In the embodiment shown in , a housing 92 is hollowed out in the rod 90, coaxially with the longitudinal axis X, which housing 92 opens outwards on the second axial end side of the rod 90. This housing 92 is a cylindrical housing or a bore which extends between the second axial end of the rod 90 and the junction zone between the rod 90 and the radial wall 72. This housing 92 may be tapped or not. In the case of a tapped housing, this housing 92 is intended to receive a fixing member 20 of the screw type making it possible to reliably maintain the equipment 2 on the head part 5.

The second fixing zone 10 is integral with the second axial end of the rod 90.

In the embodiment of Figures 2 to 4, this second fixing zone 10 is in the form of a flange 100 secured to the rod 90 and carrying an annular projection centered on the longitudinal axis X and defining a seat 101. The flange 100 and the seat 101 are concentric and coaxial with the longitudinal axis X. The diameter of the flange 100 is equal to the outside diameter of the cylindrical side wall 71. The length of the rod 90 is such that the flange 100 is at a certain distance from the radial wall 72 before the rupture of the fusible zone 6, and is able to be in the vicinity of the radial wall 72 after rupture of the fusible zone 6, or at most in contact with it.

In the embodiment of the , the flange 100 is pierced with a circular central opening whose diameter is equal to the diameter of the axial housing 92, the diameter of the seat 101 being greater than the diameter of the central opening. In this embodiment, in the mounted state, the housing 92 receives, in particular by screwing, a fixing member 20 of the equipment 2, a part of the equipment 2 is received in the opening of the seat 101 and the external face of the flange 100 comes into contact with the equipment 2.

In use, under conventional driving conditions of a vehicle inside which the fixing device 1 is mounted, the device 1 is screwed or otherwise fixed to the interior wall 3 of the vehicle via the first fixing zone 8 of the body part 4, and the equipment 2 is screwed or otherwise fixed to the device 1 via the second fixing zone 10 of the head part 5 ( ). The fusible zone 6 of the fixing device 1 is dimensioned to be able to withstand the stresses of conventional driving of the vehicle. Thus, under conventional driving conditions, the equipment 2 is reliably and fixedly retained relative to the wall 3. Due to the coaxial arrangement of the body part 4 and the head part 5, the device 1 is compact and easily mountable and dismountable.

At the time of a violent impact on the vehicle, in particular a mine-type impact, the wall 3 of the vehicle is stressed and deformed. This stress is transmitted to the body part 4 of the fixing device 1. The fusible zone 6 being dimensioned to be able to break, for example to be sheared, beyond a certain level of stress corresponding to the stress received in particular in the event of a mine impact, the fusible zone 6 breaks ( ). The head part 5 is then decoupled from the body part 4, in other words, the equipment 2 is decoupled from the wall 3 of the vehicle. Such a separation at the level of the fusible zone 6 therefore prevents the transmission of the stress received by the wall 3 to the equipment 2 fixed there. Thus, the equipment 2 does not risk being damaged or destroyed by this stress.

When the fusible zone 6 ruptures, the piston-forming element 9 is caused to move relative to the chamber-forming element 7, towards the bottom wall 70 (Figures 3 and 4). More specifically, the rod 90 moves in the cavity 74 while being guided through a central opening 720 formed in the radial wall 72 following the rupture of the fusible zone 6. This movement occurs along the longitudinal axis X. The air present in the cavity 74 can dampen the movement of the piston-forming element 9 inside the cavity 74. In another embodiment not shown, the chamber-forming element 7 can comprise vents distributed so as to allow this air to escape from the cavity 74. In yet another embodiment not shown, the chamber-forming element 7 could comprise at least one mechanical element arranged inside the cavity 74 so as to dampen the movement, in other words to ensure controlled braking, of the piston-forming element 9 inside the cavity 74.

The head part 5 to which the equipment 2 is made integral is prevented from completely exiting the cavity 74 of the body part 4 by the retention of the collar 91 in said cavity 74. Indeed, the diameter D4 of the collar 91 being greater than the diameter D1 of the fusible zone 6, a movement of the rod 90 in the direction of the radial wall 72 would bring the collar 91 into abutment against the radial wall 72 on the cavity 74 side. Thus, the head part 5 is prevented from being projected out of the body part 4, which avoids the projection of the equipment 2 at a distance from the wall 3. The piston-forming element 9, and in particular the collar 91, and the chamber-forming element 7, and in particular the radial wall 72 and the position of the fusible zone 6 thereon, constitute retention means making it possible, in all circumstances, to make the body part 4 and the head part 5 inseparable. and to keep them in direct contact with each other, and this without any intermediate or additional part between the body part 4 and the head part 5.

It is understood that the particular embodiments which have just been described have been given for information purposes and are not limiting, and that modifications may be made without departing from the present invention. For example, the body part 4 and the head part 5 could have non-circular cross-sections.

Claims

Fastening device (1) for fastening an element to be fastened (2) to a support element (3) of a structure, in particular to a wall (3) of an armoured vehicle, which fastening device (1) comprises a body part (4) capable of being secured to said support element (3) and a head part (5) capable of being secured to the element to be fastened (2), the body part (4) and the head part (5) being coaxial, a fusible zone (6) configured to break under a predetermined load connecting the head part (5) to the body part (4), the fastening device (1) comprising retaining means (7, 9) configured to, in the event of rupture of the fusible zone (6), render the body part (4) and the head part (5) inseparable and keep them in direct contact with each other, characterised in that the retaining means (7, 9) comprise a chamber-forming element (7) secured to the body part (4) and a piston-forming element (9). integral with the head part (5), the chamber element (7) defining a cavity (74) in the body part (4) and comprising a radial wall (72) which extends transversely with respect to the axis (X) of the body part (4) and the head part (5), the radial wall (72) comprising the fusible zone (6), the piston element (9) comprising an axial rod (90) passing through the radial wall (72) and a radial collar (91) formed around the rod (90) and received in the cavity (74), the chamber element (7) and the piston element (9) being configured such that in the event of rupture of the fusible zone (6), the rod (90) is able to slide in the cavity (74) and the collar (91) is retained in the cavity (74) by abutment against the radial wall (72).
Device (1) according to claim 1, characterized in that the fusible zone (6) comprises at least one reduced section calibrated at break.
Device (1) according to any one of claims 1 and 2, characterized in that the chamber-forming element (7) is an element defining a cylindrical cavity (74), the piston-forming element (9) is a cylindrical element comprising a cylindrical rod (90) and a cylindrical collar (91), and the fusible zone (6) is an annular zone, the diameter (D1) of the annular zone being greater than the diameter (D3) of the rod (90) and less than the diameter (D4) of the collar (91).
Device (1) according to any one of claims 1 to 3, characterized in that the chamber-forming element (7) comprises a plurality of vents configured to allow air to escape from the cavity (74).
Device (1) according to any one of claims 1 to 4, characterized in that at least one mechanical element is arranged inside the cavity (74) so as to dampen the movement of the head part (5) relative to the body part (4) in the event of rupture of the fusible zone (6).
Device (1) according to any one of claims 1 to 5, characterized in that it comprises, at one of its axial ends, a first fixing zone (8) integral with the body part (4), in particular a male zone, and, at the other of its axial ends, a second fixing zone (10) integral with the head part (5), in particular a female zone, the first (8) and second (10) fixing zones being coaxial.
Device (1) according to any one of claims 1 to 6, characterized in that it is made of plastic or metal.
Device (1) according to any one of claims 1 to 7, characterized in that the device (1) is a single-piece part capable of being produced by 3D printing or by an additive manufacturing process.