High-capacity, very long-range, and rapid-launching folding mobile bridge from a ground vehicle

Abstract

The invention relates to a long-span, mobile, folding bridge for all types of vehicles, easily transportable by road and rapidly deployable between the points it needs to connect. A single heavy truck is sufficient to transport it, and its crossing capabilities provide a clear tactical advantage to any armed force using it, as well as a rapid response capability to disasters for its civilian applications. The invention also details an optional propulsion system enabling automatic deployment in a few tens of seconds. Figure to be published with the abstract: Figure 1.

Description

Title of the invention: High-capacity, very long-span, rapid-launching folding mobile bridge from a land vehicle. Technical field

[0001] The invention relates to the field of rapid installation bridges, temporary or not, allowing access for light and heavy vehicles to be established or restored in a very short time between two points separated by a natural or artificial obstacle, such as a river, a ravine, an underlying road or a landslide, which can be useful both in a military context, to allow vehicles of an armed force to cross the obstacle at the place and time of its choice, or in a civilian context, to replace a damaged bridge, restore access to a disaster area or serve as a primary structure for a more elaborate bridge. Previous technique

[0002] The bridges used so far employ, for long wet obstacles, a succession of floating modules and require a substantial workforce of several dozen operators and low banks.

[0003] For dry obstacles, they use a manual or automated in situ assembly of prefabricated sections whose height, limited by the capacities of the road network, prevents the crossing of distances greater than a few tens of meters.

[0004] Both require several tens of minutes to deploy and a previously secured environment. Description of the invention

[0005] The present invention relates to a mobile bridge that can be folded and transported in a single vehicle, with a very long range and rapid launch, as well as a propulsion system that allows, under certain conditions, automatic and near-instantaneous deployment thanks to a matrix of solid propellant thrusters. Benefits provided

[0006] The bridge described here is transportable in its folded state in a single heavy vehicle suitable for circulation on the vast majority of the road network, without this preventing it from reaching lengths once unfolded exceeding one hundred meters without an intermediate pier and, simultaneously, support capacities exceeding sixty tons, i.e. a battle tank for military applications or an entire lane of light vehicles for civil applications.

[0007] In addition to its long span, its advantages over existing folding bridges are numerous. Its lightness makes it possible to deploy it almost statically using a river crane or a heavy-lift helicopter.

[0008] When it uses its propulsion matrix, it can overcome the obstacle very quickly, in a few seconds or tens of seconds, and automatically, thus not requiring a ground crew. It therefore offers a clear advantage both in a military context, with its ability to be deployed immediately in a relatively hostile and unsecured environment, and in a civilian context, allowing for unparalleled speed of response to disasters.

[0009] For crossing a river or stream, it also offers the advantage of not requiring low banks because it does not rely on the water and can therefore be adapted to raised quays.

[0010] More generally, it allows for very strong adaptability to the terrain and deployment conditions: it will compensate for wind, slope and elevation as well as the type and stability of the soil, without preparation, making it very useful for military and civil emergency applications. Brief description of the drawings

[0011] Fig. 1 is a side view of the bridge in folded configuration, before unfolding, as transportable on public roads using a heavy goods vehicle, the front being on the right by convention and therefore the rear on the left, showing the frames (1), the half-decks (2), the initial (3) and final (4) points, the matrix (11), the protective cushions (14) and the controller (13), without the bases (5) and obliques (6) relaxed for clarity.

[0012] Figure 2 is a side view of part of the bridge elements during the quasi-vertical unfolding phase, showing a segment in tension, a segment being tensioned, and a segment still folded. In this view, the bridge will begin its descent on the left side.

[0013] Fig. 3 is a side view of the entire bridge once fully deployed, after the controlled lowering phase and ready to receive vehicles.

[0014] Fig. 4 is an isometric view, from the rear, of a segment between two frames being unfolded, showing the half-aprons (2), bases (5) and obliques (6) not yet stretched, drops (7), crossbars (8) and bars (10).

[0015] Fig. 5 is an exploded isometric view, from the front, of the assembly connecting two successive frames, showing the half-decks (2), downpipes (7), crossbeams (8), stops (9) and bars (10).

[0016] Fig. 6 is a bottom view of an example of a propulsion matrix (11) with its thrusters (12), distributed here into 90 unfolding thrusters (12), all oriented in slightly different directions from each other and 56 lowering thrusters (12).

[0017] Fig. 7 is an isometric view of the same example matrix (11) with its propellants (12). Detailed description 1. General Mechanical Structure

[0018] The bridge is presented in the folded form as in [Fig. 1], in dimensions easily transportable on the road network, by a stacking of a number of horizontal frames (1), identical in all their design except for their dimensions and connected to each other by various elements described below including the half-decks (2), to which are added two extreme elements, the initial (3) and final (4) points.

[0019] Its launch consists of an unfolding and lowering which can be done by slings using a crane or a transport helicopter for slower but precision applications or using the optional propulsion matrix (11), for urgent applications; matrix which is a solid propellant propulsion system (12). 2. Frameworks

[0020] Each frame (1), described in figures 4 and 5, is made up of two types of parts: the downs (7) and the crossbars (8).

[0021] The descents (7) are two horizontal bars, parallel and arranged lengthwise at the left and right ends of the frame, intended to be positioned vertically when the bridge is unfolded, therefore the length of which will determine the height of the unfolded bridge.

[0022] The crossbars (8) are two horizontal bars, parallel and arranged in the width direction at the front and rear ends of the frame, connecting the downpipes (7) perpendicularly to each other to form a rectangular frame defining the frame.

[0023] The downpipes (7) have the role within the unfolded bridge of transmitting compressive shear forces and therefore generally, but not necessarily, have an advantage in having a tubular and rectangular section, in order to best resist buckling while stacking properly in the folded state, and in being made of a standard construction steel such as S355.

[0024] The crossbeams (8) will serve, during the unfolding of the bridge, as an axis of rotation of other parts defined below while transmitting certain forces within the unfolded bridge, and therefore have an advantage in having a circular, solid or tubular section.

[0025] Each frame is connected, as shown in [Fig.4], to the next by three types of parts: the half-aprons (2), the obliques (6) and the bases (5). 3. Aprons

[0026] Each deck, horizontal in its folded configuration, is formed of two half-decks (2) connected by a cylindrical bar (10) similar to the crossbeams, arranged against each other in opposition and freely rotating around this bar (10), as shown in the Figures 4 and 5. The lower half-deck (2) is pivoted by rotation around the front cross member (8) of the lower frame (1), and the upper half-deck (2) is pivoted by rotation around the front cross member (8) of the upper frame (1). Together, they form a three-pivot joint system, located at the front of the two frames (1) that they connect and are designed to unfold to form a horizontal or near-horizontal deck after the bridge is lowered, which will constitute a portion of the vehicle traffic lane, while transmitting a compressive force naturally inherent in the upper horizontal portions of the beams subjected to simple bending on two supports, as the unfolded bridge will be.

[0027] The half-decks (2) may, advantageously but not necessarily, be covered, on their upper surface once the bridge is unfolded, with a bituminous coating to provide traction for vehicles crossing. They are of a similar thickness to the ramps (7). Their construction may, but is not required, as shown in [Fig. 5], involve horizontally placed plates, distributed across their width and having sections with holes at both ends, acting as hinges, joined, for example by welding, to a horizontal plate.

[0028] The half-decks (2), as can be seen in Figures 2 and 5, are in a plane slightly offset from their axis of rotation around the cross members (8) and the bars (10), and are equipped with a stop (9) on their front edge, preventing the assembly from rotating at an angle exceeding the parallelism of the half-decks (2), so that once unfolded, they form a stable, compression-resistant, and straight system. This stability is reinforced by the fact that gravity, once the bridge is unfolded, will force the half-decks (2) to remain in their maximum stop position. If necessary, to further enhance this kinematic stability, torsion springs can be used around the axis (10) connecting the two half-decks (2), forcing these half-decks (2) to remain in their maximum stop position.

[0029] This offset construction necessitates the prominence, at the level of the cross members (8), as visible in Figures 2 and 5, of the hinges of the half-decks (2), extending above the traffic lane by half the thickness of the frame (1). To avoid obstructing the passage of vehicles, rollers or cylinders of the same diameter can be added to fill the gaps within these hinges, preventing the tires or tracks of the vehicles from being damaged by contact with them. 4. Bases and obliques

[0030] The bases (5), visible in Figures 2 and 4, are two cables each connecting the rear cross members (8) of the consecutive frames (1) at their respective left and right ends, near their connections with the down members (7), allowing the transmission of the tensile stress naturally constituting the lower horizontal portions of the beams subjected to simple bending on two supports. Their mode Since the main failure is therefore exceeding the elastic limit of the material, they will advantageously, but not necessarily, be made of a steel with high specific elastic strength.

[0031] Finally, the diagonal braces (6) are four cables, shown in Figures 2 and 4, arranged in two symmetrical groups, on the left and right sides, advantageously but not necessarily made of high specific yield strength steels. Each group contains two cables, one connecting the front end of the lower frame (1) drop (7) to the rear end of the upper frame (1) drop (7), and the other connecting the front end of the upper frame (1) drop (7) to the rear end of the lower frame (1) drop (7). They are of a length adjusted to be substantially greater than the length of the drops (7) they connect, so that once the bridge is unfolded and in a horizontal position, they form a cross connecting the opposite corners of the quadrilateral formed by the drops (7), the pair of half-decks (2), and the bases (5) located between the two frames they connect.

[0032] The role of the diagonal braces (6) is obviously to ensure the continuous transmission of shear forces along the unfolded bridge. Depending on the stress profile inside the bridge and therefore the distribution of the loads to which it will be subjected, the shear force will be transmitted from one frame (1) to the other, symmetrically on the left and right sides, by one of the two diagonal braces (6) being in tension, the other being unaffected. The downslopes (7), however, will always be in compression.

[0033] The bases (5) and oblique elements (6) may be replaced, equivalently, by any element or assembly that allows the transmission of a tensile force while retaining the ability to adapt without resistance to a compressive stress in order to conform to the folded configuration of the bridge. This includes cables, of course, but also chains or assemblies of several consecutive rods that move freely between them.

[0034] The bases can, if necessary but not necessarily, be supplemented by two other cables or assemblies for transmitting tensile forces, this time placed in a cross shape, i.e., connecting the left end of the rear cross member (8) of the lower frame (1) to the right end of the rear cross member (8) of the upper frame (1), and vice versa. Thus, the tube formed by the bridge during deployment will have its four faces equipped with resistance to shear forces, which will considerably increase its torsional stiffness and may, under certain conditions, facilitate the deployment of the bridge.

[0035] Each of the bases (5) and the opposing pairs of half-decks (2) have an approximately equal length, so that, in the unfolded and horizontal deck, the descents (7) remain vertical while accommodating the height differences between the frames (1) successive. Indeed, for optimal construction, but not necessarily, the bridge should have a variable height, maximum in the middle and minimum at the ends, because the bending moments are lower there and vehicle access will be easier. Thus, the middle frames (1) will be higher and the end frames (1) will be lower. 5. Initial and final spikes

[0036] The initial tip (3), located under the frames (1) in the folded configuration, as shown in [Fig. 1], is formed of a rigid portion similar to the decks in material and cross-section, serving as a vehicle access ramp from the ground, supporting the continuation of the compressive forces of the decks, and attached, before unfolding, at its front end by a pivot joint to the front cross member (8) of the lowest frame (1). It is connected by bases (5), supporting the continuation of the tensile forces of the adjacent bases (5), from its rear end to the left and right ends of the rear cross member (8) of the nearest frame (1). It has a flat portion at its rear end intended to serve as a support area for the weight of the assembly formed by the bridge and the vehicle crossing it during use.This flat portion may be covered with a protective cushion (14) of rubber, elastomer or any other equivalent material allowing optimal adhesion of the bridge to the ground, distribution of vertical support forces and damping for the lowering phase of the bridge.

[0037] The final tip (4) is mechanically similar to the initial tip (3), but located symmetrically above the frames (1), and contains the propulsion matrix (11) of the bridge which will allow the unfolding. 6. Mechanical stability and variants

[0038] This construction allows, as can be seen in [Fig. 3], once the bridge is unfolded, for each element described above to automatically settle into its correct mechanical operating mode, under the simple effect of gravity. The bridge thus exerts no force other than a vertical one on the ground on which it rests.

[0039] By adjusting the lengths of the bases (5) and the obliques (6), it is possible to give the unfolded bridge a more curved back with a flat belly, for example for military applications where the slope of the traffic lane is of little importance but where the unevenness of the terrain could create an undesirable contact between the ground and the ramps (7) or between the ground and the bases (5), or a more curved belly with a flat back, for example for civil applications where the slope of the traffic lane is important but where space is available below the access points to the bridge, such as raised quays for example.

[0040] One of the major advantages of this structure is that it minimizes the length of parts subjected to compression. Indeed, for the same nominal force applied, a part designed for compressive stress will very often be much heavier than an equivalent part designed for tensile stress, in order to prevent buckling. Here, only the decks, abutments, and downslopes are in compression, which saves a significant amount of material and thus results in a high-capacity bridge that remains transportable on the road network. 7. Quasi-static deployment

[0041] A quasi-static deployment of the bridge is possible for applications requiring precision or when deployment by propulsion matrix is ​​unusable, for example for civil applications in dense urban areas.

[0042] This can be done using a mobile river crane if the obstacle to be crossed is a watercourse, or using a heavy-lift helicopter. It consists of lifting the bridge by its end section (4) using slings and lowering it to the arrival point, unfolding the bridge segment by segment. The lifting device, at any given moment, and provided that the deployment trajectory remains sufficiently close to the horizontal so that the diagonal braces (6) remain taut, thus transmitting the shear forces along the structure, only has to support half the weight of the bridge, the other half being supported by the initial section on the ground, which makes it compatible, in its lighter versions, with deployment by a heavy-lift helicopter.

[0043] Its foldable nature also makes it possible to fold it back up for subsequent reuse using a quasi-static method, naturally following the reverse process of that described above, whether the unfolding was done quasi-statically or dynamically. 8. Dynamic Deployment

[0044] A dynamic deployment of the bridge is possible in a completely autonomous manner in a few tens of seconds thanks to a propulsion matrix (11) described below.

[0045] As shown in Figures 6 and 7, it consists of an integrated thrust transmission structure, for example, in the tail section (4), located beneath and attached to its rigid upper portion. It houses solid propellant thrusters (12). These thrusters are designed to provide the thrust necessary for deploying the bridge in two successive phases: unfolding in the air, a vertical or near-vertical upward phase, and controlled lowering, by rotation around its lower support axis, which is the tip of the initial section (3), once the latter is in the upright position after all segments have been deployed. This matrix serves to hold, fixed to it in a precise direction, a large number of small thrusters (12) capable of delivering their thrust rapidly upon electronic control, and is made of the A suitable structure, for example metallic, is required to ensure that the thrust from each thruster is efficiently transmitted to the final tip and thus to the rest of the bridge during deployment. Each thruster (12) is oriented at a slightly different angle within the matrix (11), so that electronic control of their activation allows for real-time adjustment of the bridge's deployment trajectory.

[0046] The technology of these solid propellant thrusters is sufficiently safe and well controlled at present for the bridge to be permanently ready for deployment, subject, of course, to the usual regular inspections.

[0047] An electronic controller (13) equipped with sensors capable of measuring the position of the end tip relative to the initial support and to the ground, as well as the speed, acceleration, and orientation of the various bridge elements, is integrated into the end tip (4). It can thus easily be equipped with a secure remote triggering system, allowing the bridge's user, whether civilian or military, to deploy it safely and efficiently. During deployment, the controller (13) decides when to trigger each thruster (12) based on the requirements for instantaneous deployment control, in terms of the total thrust required and its orientation.

[0048] Deployment begins by positioning the rear of the carrier vehicle towards the obstacle to be crossed, perpendicular to it. The controller (13), activated by the operator, starts the automated process.

[0049] It begins with the unfolding stage, which consists first of activating one or more thrusters (12) to orient the final tip (4) into its vertical position, with the bases extended. Then, other thrusters (12) activate to start the quasi-vertical ascent phase, shown in [Fig. 2] and [Fig. 4], unfolding, one by one, all the half-decks (2), extending the bases (5) and the obliques (6), and distributing the frames (1) along the entire length of the bridge. The thrust is adjusted by the controller (13) to be low at the beginning and increasingly greater to support almost all the weight of the unfolded bridge, which remains slightly supported on the end of its initial tip (3), the latter becoming vertical at the end of this phase. Depending on the speed limitations of unfolding the half-aprons (2) and the tension of the cables (5 and 6) to preserve them, the unfolding phase lasts from 10 to 20 seconds.

[0050] Finally, the lowering step consists of letting the unfolded bridge fall while rotating around the end of the initial tip (3), therefore counterclockwise and to the left in Figures 1 and 2, while continuing to trigger certain thrusters (12) in the direction of the bridge's traction in order to keep it taut during its fall, and then triggering the thrusters (12) necessary to control its lowering so that it slows down and reaches the ground at a speed close to zero, remaining within the range absorbable by the intrinsic elasticity of the bridge and the damping of the protective cushion (14) located under the final tip (4), the bridge then being in its final horizontal position as in [Fig.3]. This lowering stage lasts approximately 5 to 10 seconds after activation of the lowering thrusters (12).

[0051] At the end of the lowering phase and during the bridge's resting on the ground, gravity and the compression of the half-decks (2) ensure that they are in a stable, maximum-stop engaged position and that the bases (5) are under tension. The height of each frame (1) relative to the ground will adjust so that each group of two crossed diagonal braces (6) contains at least one diagonal brace under tension due to the transmission of the shear force within the bridge.

[0052] The bridge is designed not to be fixed to its carrier vehicle, or at least only to be fixed to it during transport. Thus, its upward inertia and the thrust of the thrusters (12) can, for example at the end of the unfolding phase, extract it from its carrier vehicle by sliding or jumping its lowest part, i.e., its initial tip (3), backwards, if necessary by using a stop provided for this purpose on the carrier vehicle to orient the movement of the initial tip (3) backwards. The carrier vehicle is then free to move and the bridge is ready for use.

[0053] This deployment method offers several advantages over the quasi-static method. The first is that it does not require counterweights to prevent the lifting system from tipping, which would be very difficult to implement for a span of up to one hundred meters. The bridge is supported by the reaction of the thrusters (12) throughout its deployment. The second is that adaptations to the terrain and local operating conditions of the bridge, such as slope, cross slope, wind, soil type, or soil stability, are made automatically by instantaneous electronic control of the thrust via the activation of the appropriate thrusters (12): a crosswind or cross slope will be compensated for by using more thrusters (12) on one side than the other, etc. The third is the deployment time, which is measured in seconds and not in minutes or hours.The fourth is the absence of a need for a human operator, making the bridge deployable more easily, by a larger staff, and more immediately. Examples

[0054] We give here an example of the construction of the bridge which is the subject of the invention, with a military variant and a civilian variant.

[0055] Of course, the dimensions shown below are not mandatory and any construction may adapt these figures according to its needs.

[0056] An example of a reference bridge contains 10 frames (1) and, when unfolded, has a span of 100 meters, a central height of 8 meters, an extreme height of 3 meters, and dimensions in folded configuration of 16 meters. It is 3.5 meters long and high and has a total mass of less than 30 tons, making it easily transportable on a land vehicle.

[0057] Such a mass also makes it possible to deploy it almost statically by heavy transport helicopter, the most powerful models having a lifting capacity exceeding 16 tonnes, i.e. more than half the mass of the bridge.

[0058] For military applications, it may have a support capacity of 60 tonnes in point load with a safety factor of 2 and a 4-meter wide track, allowing a battle tank to pass and, for civil applications, a support capacity of 20 tonnes in point load, allowing some heavy goods vehicles to pass, and 120 tonnes in uniformly distributed load, allowing an entire lane of light or medium utility vehicles to pass, again with a safety factor of 2 and a 3-meter wide track.

[0059] The frames (1) may have a stacking height of 30 centimetres, with drops (7) of length from 3 to 8 metres and of cross section 300 x 100 x 6 mm, in S355 steel. The cross members (8), for their part, may have a cross section of 120 x 6 mm, in the same material, joined to the drops (7) by welding, for example.

[0060] The half-decks (2) may be 5 meters long and, for civilian applications, made of 6 vertical plates, 10 mm thick, ending in perforated sections acting as hinges, and reinforced at this point to resist local stresses, made of S355 steel and joined, for example by welding, to a horizontal plate 5 mm thick of the same material, with stops (9) at their ends touching the bars (10), also made of the same material. For a military application, given the concentration of the load not uniformly but on a single deck, as in the case of a battle tank, 7075 aluminum may be chosen, assembled by riveting, with thicknesses of 20 mm for the 6 vertical plates and 10 mm for the horizontal surface plate.

[0061] For preferential use in a quasi-static deployment, the logistical ease of the system can be significantly increased by replacing the 7075 aluminum in the design of the half-decks (2) with a carbon fiber-epoxy composite. This choice reduces the total mass of the bridge to approximately 9 tonnes and therefore the mass to be lifted by the helicopter to 4.5 tonnes, considerably increasing the number of aircraft capable of the operation.

[0062] The initial (3) and final (4) points can be made with the same section as the half-aprons (2), completed by similar sheets for their extreme triangle.

[0063] The bases (5) may be made of high-strength carbon steel cable with a width of 40 mm, and the obliques (6) of cable of the same material with a width of 20 mm.

[0064] The propulsion matrix (11) may be made, advantageously but not necessarily, of four S355 steel sheets, if necessary bent, and perforated to accommodate the thrusters (12), accompanied by possible reinforcements.

[0065] Its indicative propulsion requirements, taking into account a safety margin to absorb differences in deployment conditions such as wind or elevation, are a total thrust of 750 kNs for the deployment phase and 500 kNs for the lowering phase, requiring a total of approximately 125 small thrusters of 7 kg each, each providing a thrust of around 10 kNs, each measuring 9 centimeters in diameter and 90 centimeters in length and operating on a common propellant such as a mixture of ammonium perchlorate and aluminum, bound by a polymer such as HTPB, forming an assembly with a mass of approximately 1 tonne, supported by a matrix (11) of approximately 1 tonne, the propulsion stage thus remaining negligible compared to the mass of the rest of the deck. This system can, of course, also be dimensioned differently depending on the requirements.

Claims

Demands

1. Mobile folding and transportable bridge, characterized in that it is formed of several stackable frames (1) transmitting the shear compression forces, connected by pairs of rigid pivoting half-decks (2) with stop (9) transmitting the upper horizontal compression forces, bases (5) transmitting the lower horizontal tensile forces and obliques (6) transmitting the shear tension forces, completed by initial (3) and final (4) points allowing vehicle access.

2. Automatic deployment system for a mobile bridge according to claim 1, characterized in that it uses a propulsion matrix (11) holding solid propellant thrusters (12), each oriented in a precise direction and activated at the right time by an electronic controller (13) equipped with kinematic sensors determining at each instant the thrust required for the deployment movement of the bridge to bring one end of it to the other side of the obstacle to be crossed.

3. Automatic deployment system according to claim 2, characterized in that the propulsion matrix (11) consists of a thrust transmission structure integrated into the end tip (4) and located under its upper rigid portion and fixed thereto, and in that the electronic controller (13) is integrated into the end tip (4), allowing autonomous deployment of the mobile bridge.

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