Fixing device with decoupling and anti-projection functions

Abstract

The invention relates to a fastening device (1) for attaching an element to be fastened to a support element of a structure, in particular to a wall of an armored vehicle. This fastening device (1) comprises a body (4) adapted to be attached to said support element and a head (5) adapted to be attached to the element to be fastened. The body (4) and head (5) are coaxial. A fusible zone (6) configured to rupture under a predetermined load connects the head (5) to the body (4). The device is characterized in that it includes retaining means (7, 9) configured to, in the event of rupture of the fusible zone (6), render the body (4) and head (5) inseparable and maintain them in direct contact with each other. Figure to be published with the abbreviation: Figure 2.

Description

Title of the invention: Fixing device with decoupling and anti-projection functions

[0001] 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.

[0002] The fixing device according to the present invention is particularly suitable for military use, in particular for fixing equipment to an interior wall of an armored vehicle.

[0003] As is known, the equipment inside an armored vehicle is generally fixed to the interior wall of the vehicle by fixing devices comprising spacers or columns.

[0004] For example, French patent FR2670842 is known, 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.

[0005] 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.

[0006] However, when an explosive device, for example a blast mine, is activated near the structure, such fixing 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 fixing devices are likely to be sheared and therefore the equipment is violently projected inside the structure, thus constituting a vulnerable projectile.

[0007] To partially overcome these drawbacks, French patent FR3036145 proposes using a fixing appendage comprising two parts separated by a weakened zone calibrated for breaking. Thus, when a load exerted on the appendage exceeds the acceptable load level at the weakened zone, the appendage breaks. Such a break makes it possible to limit the transmission of the stress received by the structure to which the appendage is fixed.

[0008] Furthermore, this patent proposes to equip this appendage with a flexible link capable of retaining the part of the appendage 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 appendage are kept together and at a moderate distance from each other. Such a flexible connection therefore prevents part of the appendage from being projected in the event of rupture of the weakened area, which could injure a person located near the appendage or damage nearby equipment.

[0009] However, such a fixing device comprises several parts, in particular a flexible link which 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 which 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.

[0010] 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 column or spacer under normal mechanical stresses, 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.

[0011] 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 armored 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, characterized in that it comprises 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.

[0012] 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 function of decoupling between the element to be fixed and the support element thanks to the presence of a fusible zone, and a function of anti-projection of the element to be fixed and of maintaining its position following decoupling thanks to the presence of the retaining means.

[0013] The decoupling function makes it possible to avoid, during a mine explosion type event, the full transmission of shock or impact energy to the element to be fixed via the fixing device.

[0014] The retaining means allow the body part and the head part not to become disjointed following decoupling, in other words to prevent the head part from being projected 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.

[0015] Preferably, the fusible zone comprises at least one reduced section calibrated at break.

[0016] The reduced section can be defined for example by at least one of the following means: notch, groove, slot, striation, groove or the like.

[0017] In a particular embodiment, the retaining means comprise a chamber-forming element secured to the body portion and a piston-forming element secured to the head portion, the chamber-forming element defining a cavity in the body portion and comprising a radial wall which extends transversely relative to the axis of the body portion and the head portion, the radial wall comprising the fusible zone, the piston-forming element comprising an axial rod 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.

[0018] Thus, 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.

[0019] 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.

[0020] 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-forming element relative to the chamber-forming element during a rupture of the fusible zone.

[0021] The chamber-forming member may include a plurality of vents configured to allow air to escape from the cavity.

[0022] Such vents, depending on their number, their dimensions and their positioning, make it possible to control the speed of movement of the piston-forming element relative to the chamber-forming element following decoupling between the head and body parts.

[0023] 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.

[0024] The presence of at least one such mechanical element therefore allows movement progressive and braked movement of the head part following its decoupling from the body part.

[0025] 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.

[0026] The first attachment zone may be a male rod, with or without threads, and the second attachment zone may be a female bore, with or without threads.

[0027] 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.

[0028] The device can be made of plastic or metal.

[0029] Advantageously, the device is a single-piece part capable of being produced by 3D printing or by an additive manufacturing process.

[0030] Thus, the fixing device can be produced simply and quickly. Such manufacturing techniques allow for great adaptation, even custom manufacturing.

[0031] The present invention will be better understood on reading the following description of a particular embodiment, a description made in light of the appended drawings, drawings in which:

[0032] [Fig-1] shows in longitudinal section a fixing device according to the invention, fixed to a wall and carrying equipment;

[0033] [Fig.2] represents in longitudinal section a fixing device according to the invention, in its configuration before rupture of the fusible zone;

[0034] [Fig.3] represents in longitudinal section the fixing device of [Fig.2], following the rupture of the fusible zone; and

[0035] [Fig.4] is a perspective view of the fixing device of [Fig.3] following the breakage.

[0036] Referring firstly to [Fig. 1], 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.

[0037] As can be seen in Figures 1 to 4, the fixing 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 fixing device 1 is a monobloc type part, that is to say 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.

[0038] 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, the body part 4 comprises a chamber-forming element 7 and a first fixing zone 8.

[0039] 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 it. 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 with a diameter DI 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.

[0040] It should be emphasized that the fusible zone 6 may be a zone of lesser thickness, a zone comprising at least one crack or any other fatigue zone capable of breaking under a predetermined load.

[0041] 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-forming element 7.

[0042] Flats (not shown) may be provided on the cylindrical side wall 71 in order to serve as bearing surfaces for a wrench or a screwing tool, thus facilitating the fixing of the device 1 to the wall 3.

[0043] 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 presented 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.

[0044] 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-forming element 9 and a second fixing zone 10.

[0045] 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 DI 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.

[0046] The collar 91 is in the form of a disc 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 DI 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.

[0047] In the embodiment shown in Figures 2 to 4, the axial rod 90 is a solid rod. In the embodiment shown in [Fig.l], 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 or may not be threaded. In the case of a threaded housing, this housing 92 is intended to receive a screw-type fixing member 20 making it possible to reliably hold the equipment 2 on the head part 5.

[0048] The second fixing zone 10 is integral with the second axial end of the rod 90.

[0049] 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 a projection annular 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 near the radial wall 72 after rupture of the fusible zone 6, or at most in contact with it.

[0050] In the embodiment of [Fig. 1], 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.

[0051] 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 ([Fig.l]). 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 mounted and dismounted.

[0052] 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 capable of breaking, for example of being 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 ([Fig. 3]). 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 which is fixed there. Thus, the equipment 2 does not risk being damaged or destroyed by this stress.

[0053] 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 precisely, 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 displacement 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.

[0054] The head part 5 to which the equipment 2 is made integral is prevented from leaving the cavity 74 of the body part 4 completely by the retention of the collar 91 in said cavity 74.Indeed, the diameter D4 of the collar 91 being greater than the diameter DI 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 prevents the equipment 2 from being projected away 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 retaining 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.

[0055] It is understood that the particular embodiments which have just been described have been given for informational and non-limiting purposes, 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

Claims

1. Fastening device (1) for fixing an element to be fixed (2) on a support element (3) of a structure, in particular on a wall (3) of an armored 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 fixed (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), make the body part (4) and the head part (5) inseparable and keep them in direct contact with each other, characterized in that the retaining means (7, 9) comprise a chamber-forming element (7) secured to the body part (4) and a chamber-forming element piston (9) secured to the head part (5),the chamber-forming 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 of the head part (5), the radial wall (72) comprising the fusible zone (6), the piston-forming 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-forming element (7) and the piston-forming 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).,

2. Device (1) according to claim 1, characterized in that the fusible zone (6) comprises at least one reduced section calibrated at break.

3. 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).

4. 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).

5. 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).

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.

7. Device (1) according to any one of claims 1 to 6, characterized in that it is made of plastic or metal material.

8. 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.

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