Roof rollover assembly

Abstract

The invention relates to a roof rollover assembly (10) for a vehicle (90), comprising a roof cross member (20) extending transversely to the direction of travel between the opposite sides of the vehicle, two crashbox profiles (30) each connected at one end to the roof cross member (20) and having a force-conducting connection to a body pillar such as a B-pillar (70) and / or a C-pillar (80) and / or a D-pillar, wherein the connection between the roof cross member (20) and the crashbox profiles (30) is designed such that forces occurring are directed into the crashbox profiles (30), and wherein the crashbox profiles (30) are designed such that they are plastically deformable in the event of a vehicle rollover to absorb and dissipate impact energy.

Description

The invention relates to a roof rollover assembly for the roof area of ​​a motor vehicle, which serves to ensure the safety of the vehicle occupants in the event of a vehicle rollover. Modern vehicle bodies incorporate numerous design measures to improve the passive safety of vehicle occupants in accidents. A key focus is the targeted energy absorption through structured body elements, in order to effectively dissipate the forces acting on the vehicle and redirect them to load-bearing body structures. In addition to crumple zones in the front and rear areas, and reinforced side sills to absorb frontal and side impact forces, rollover protection is becoming increasingly important. This is especially true for vehicle concepts with a high center of gravity – such as sport utility vehicles (SUVs), vans, and crossover models – as well as for bodies with an open roof structure, such as convertibles or roadsters. In these cases, the structural load-bearing capacity in the roof area is often limited or inherently weaker due to the design. Effective rollover protection therefore requires additional structural measures in the upper body area to safeguard the occupants' survival spaces and prevent critical roof deformation in the event of a rollover. Integrating such protective measures presents not only design challenges, but also manufacturing and weight-related ones, particularly with regard to modern lightweight construction concepts and cross-platform modularity. Various solutions are already known from the prior art in which cross members are attached between the B-pillars to absorb impact forces and transfer them into the vehicle structure. German patent DE 10 2017 118 780 A1 describes a modular system for a protective device in motor vehicles, designed to protect vehicle occupants in the event of a rollover. The core components of this protective device are a crossmember for absorbing side impact forces and a left and a right support structure for connection to the respective B-pillars. The crossmember is connected to the two support structures via fasteners, in particular screws. These fasteners pass through the support structures and allow for additional connection to the engine housing and / or the engine compartment. This achieves a distribution of the impact forces across multiple load paths, namely the B-pillars, the engine housing, and the vehicle body structure. German patent application DE 10 2019 107 866 A1 describes a roll bar for dissipating impact forces in a motor vehicle. The system comprises a crossmember that absorbs loads in the Y-direction, at least one roll bar that transfers the impact forces to the crossmember, an intermediate piece for attaching the crossmember to a support column, in particular the B-pillar, and a fastening device that connects the crossmember and the roll bar to the intermediate piece. A key feature of this fastening device is a base plate that is placed on top of the intermediate piece and transmits vertical forces in the direction of this column. DE 10 2017 118 779 A1 relates to a modular system for a protective device that protects vehicle occupants in the event of a vehicle rollover. The device comprises a crossmember for absorbing side impact forces and two lateral support devices for force-transmitting attachment to the vehicle's B-pillars. The crossmember is connected to the support devices via fasteners that also pass through the support devices and allow for connection to other vehicle structures such as the engine bell housing and / or the body. JP S56-2613Y2 describes a protective device for agricultural vehicles with a safety frame surrounding the vehicle to protect the driver in the event of a rollover. A deformable energy absorption element is arranged between the upper and lower frame sections; this element is deformed in a controlled manner during a rollover, thereby absorbing and reducing impact forces. DE 201 21 532 U1 relates to a bumper for a motor vehicle with a cross member connected to the longitudinal members via crash boxes. The crash boxes are designed as hollow metallic profiles and have at least partial internal filling with an organic foam, which increases their energy absorption capacity in the event of an impact. The foam filling particularly improves the lateral and buckling stiffness of the crash boxes, as well as achieving a favorable force-displacement curve, thus resulting in more efficient energy absorption and improved crash performance of the bumper while simultaneously reducing weight. These known systems primarily create a force-conducting connection to load-bearing body structures. However, they do not effectively absorb and reduce rollover forces in the upper roof area, or only do so inadequately. Against this background, the object of the invention is to provide a roof rollover assembly which, in the event of a vehicle rollover, enables targeted force absorption in the roof area and thus ensures that rollover forces are not directly transmitted to structurally less resilient body zones. This problem is solved according to the invention with regard to a roof rollover assembly by the features of claim 1. The further claims relate to preferred embodiments of the invention. The roof rollover assembly according to the invention enables targeted and coordinated energy absorption in the roof area of ​​a vehicle. The plastically deformable crash box profiles, in combination with a robustly designed roof cross member, contribute to the controlled dissipation of rollover forces within the roof structure. This significantly increases the structural safety of the passenger cabin in vehicle rollover events, particularly by relieving the load on less load-bearing body zones. The roof rollover assembly can be integrated into various vehicle types without significant changes to the external roof contour. This allows for flexible adaptation to different body architectures. Using simulation methods, its structure can be precisely adapted to vehicle-specific load scenarios to optimize its effectiveness and efficiency for various applications. The invention provides a roof rollover assembly for a vehicle. The roof rollover assembly comprises a roof crossmember, which is arranged in the roof area of ​​the vehicle and extends transversely to the direction of travel between the opposite sides of the vehicle, and two crashbox profiles, each of which is connected at one end to the roof crossmember and has a force-conducting connection to a B-pillar and / or a C-pillar and / or a D-pillar. The crashbox profiles are designed as extruded, multi-cell hollow profiles made of aluminum, wherein the crashbox profiles are provided with a damping material, and wherein the crashbox profiles have locally defined deformation zones with targeted wall thickness reduction or integrated predetermined bending points.The connection between the roof crossmember and the crash box profiles is designed so that any forces occurring are directed into the crash box profiles. The crash box profiles are designed to be plastically deformable in the event of a vehicle rollover, allowing them to absorb and dissipate impact energy. During a rollover onto the roof crossmember, the impact forces are directed into the crash box profiles and dissipated there through plastic deformation of the profiles and by the damping material within the roof rollover assembly, before the forces are transmitted to the vehicle body via the respective pillar. In another embodiment, the roof crossbeam is designed as a closed rectangular cross-section, U-profile or hybrid profile, in particular as an aluminum extrusion profile or in mixed construction with fiber-reinforced plastics. In particular, the connection between the roof cross member and the crash box profiles is achieved by form-fitting or material-fitting means, especially by screwing, welding or adhesive bonding. In a further training course, it is planned that the structural design of the roof rollover assembly will be carried out using numerical simulation, in particular using the finite element method (FEM), whereby the deformation behavior under combined bending and compressive loads is analyzed, and whereby the simulation includes the optimization of the force-energy ratio, the prediction of the buckling behavior and the reduction of local stress peaks. Advantageously, the simulation is supplemented by AI-supported optimization methods for creating variants with regard to cross-sectional geometry, wall thickness or material distribution. In another embodiment, the roof rollover assembly is modular and can be arranged at various positions along the longitudinal axis of the roof of a vehicle in the area of ​​the B-pillars and / or C-pillars and / or D-pillars. The invention will now be explained in more detail with reference to an exemplary embodiment shown in the drawing. Figure 1 shows a sectional view through the roof rollover assembly according to the invention along the section line AA shown in Figure 3a with a connection to the B-pillars; Figure 2 shows a perspective exploded view of the roof rollover assembly with roof cross members and crash box profiles as well as a connection to the B-pillars; Figure 3a shows a schematic side view of a vehicle, in which the position of a first roof rollover assembly according to the invention in the area of ​​the B-pillars and the position of a second roof rollover assembly in the area of ​​the further rearward C-pillars are shown; Figure 3b shows a schematic top view of the vehicle roof with the first and the second roof rollover assembly, which are arranged between the two opposing B-pillars and the two opposing C-pillars, respectively; Figure 4a shows a perspective view of a crash box profile in its initial state before a vehicle rollover event; Figure 3a shows the position of the roof rollover assembly in the vehicle roof.4b a perspective view of the crashbox profile from Fig. 4a in a partially deformed state during a vehicle rollover; Fig. 4c a perspective view of the crashbox profile from Fig. 4a in a fully deformed state after full force application. Additional features, aspects and advantages of the invention or its embodiments become apparent from the detailed description in conjunction with the claims. Figures 1 and 2 show an embodiment of the roof rollover assembly according to the invention in a sectional view and in a perspective exploded view. The roof rollover assembly 10 comprises a roof crossmember 20 extending transversely to the direction of travel between the opposite sides of a vehicle 90. The roof crossmember 20 is connected to two crash box profiles 30 arranged on either side, each of which has a force-conducting connection to a body pillar, in particular a B-pillar 70. The crash box profiles 30 are designed to plastically absorb and dissipate mechanical loads during a vehicle rollover. The plastic deformation occurs in a controlled and permanent, i.e., irreversible, manner in which the impact energy is absorbed via a defined structural deformation. The crashbox profiles 30 preferably consist of extruded aluminum hollow profiles that exhibit a good combination of lightweight construction, dimensional rigidity, and targeted deformability. The aluminum hollow profiles are preferably multi-celled or segmented to enable defined crumple zones. To further improve energy absorption, the cavities of the crashbox profiles 30 are lined or filled with a damping material 40, for example, with metallic foam such as aluminum foam or an energy-absorbing composite material. The roof crossbeam 20 can consist of a U-shaped or rectangular profile, also manufactured as an extruded aluminum profile. Alternatively, welded or bonded hybrid structures are also conceivable, for example, made of steel-aluminum combinations or with fiber-reinforced plastic segments to save further weight. The connection between the roof crossmember 20 and the crashbox profiles 30 can be positive-locking, material-locking, or made using suitable connecting elements such as bolts, welds, or adhesive bonds. It is essential that the force flows are directed into the structures of the crashbox profiles 30 without being transmitted undamped through the roof crossmember 20 to the roof sides or roof pillars of the vehicle 90. This design according to the invention results in a structurally integrated, force-dissipating rollover protection structure that absorbs significant portions of the impact energy in the roof area, thus preventing overloading of less load-bearing body segments. Figures 3a and 3b show schematic views of a vehicle 90, illustrating the position and arrangement of two roof rollover assemblies 10, 12 according to the invention in the area of ​​the B-pillars 70 and the C-pillars 80. The vehicle 90 has a load-bearing body structure consisting of an underbody, side sills, a roof frame, and several vertically arranged body pillars. These are commonly referred to as A-, B-, C-, and D-pillars. The A-pillars are located at the front of the vehicle, adjacent to the windshield, and contribute significantly to frontal and roof stability. The B-pillars 70 are positioned centrally between the front and rear doors and primarily contribute to lateral crash stability, as well as serving as mounting points for door locks and seat belts. The C-pillars 80 form the rear boundary of the passenger compartment and provide a structural connection between the vehicle roof 95 and the rear body section. A first roof rollover assembly 10 is arranged in the area of ​​the two opposing B-pillars 70, and a second roof rollover assembly 12 is arranged in the area of ​​the two C-pillars 80. Both roof rollover assemblies 10 and 12 extend transversely across the vehicle roof 95 and are positively connected at their ends to the adjacent B- and C-pillars 70 and 80, respectively. The arrangement is located above the side doors and at the transition from the door frame to the roof frame. Furthermore, D-pillars may be present, even if not shown. These are located in the rear of the body, typically behind the C-pillars, and are used particularly in vehicles with a third row of seats or a large rear end, such as station wagons or SUVs. The D-pillars contribute to the structural stability of the vehicle's rear, especially in the area of ​​the roofline and tailgate, and make an additional contribution to the overall rigidity and crash safety of the body structure. By integrating the roof rollover assemblies 10, 12 according to the invention into these supporting body pillars, a targeted force transmission and structural reinforcement of the roof area is achieved, particularly with regard to vehicle rollover scenarios. Figures 3a and 3b illustrate that the roof rollover assembly 10 according to the invention can be installed modularly at several positions along the longitudinal axis of the roof, for example, to separately protect the front and rear rows of seats. The roof rollover assemblies 10 and 12 are designed independently of each other, but can also interact systemically if required, for example, in a vehicle rollover event with multiple impacts or in a diagonal impact scenario. In such cases, both roof rollover assemblies 10 and 12 interact in an energetically coordinated manner via the vehicle roof 95, thus improving the overall effectiveness of the rollover protection structure. The integration into the vehicle roof 95 is carried out in such a way that the outer contour of the vehicle 90 remains largely unchanged. The roof rollover assembly 10 can optionally be designed as a permanently integrated standard component or as a retrofittable additional unit. Figures 4a to 4c show the functioning of a crashbox profile 30 in a vehicle rollover event in a schematic-perspective sequence. Fig. 4a shows the crashbox profile 30 in its initial state without load. The extruded crashbox profile 30 preferably has a multi-cell hollow structure with defined wall thicknesses and optionally reinforcing ribs. The cavities are filled with a damping material 40, for example, an aluminum foam or an energy-absorbing composite material. Fig. 4b shows the same crashbox profile 30 in a partially deformed state during a vehicle rollover event. An external force, for example, from the vehicle roof 95 contacting the ground, acts on the roof structure and is selectively converted into plastic deformation by the crashbox profile 30. The internal structure of the crashbox profile 30 begins to buckle or bulge, thereby converting and dissipating the applied energy as deformation work. Fig. 4c shows the crashbox profile 30 in its deformed final state after full force application. The original cross-section is partially or completely folded, with the damping material 40 contributing to energy absorption. The deformation occurs locally within specifically designed sections of the crashbox profile 30, thus relieving stress on the adjacent body structures. The described functional unit of the crashbox profile 30 creates a targeted, controlled deformation that absorbs high amounts of energy without overloading the adjacent structural areas of the vehicle 90. This results in a significantly improved protective effect for the occupants in vehicle rollover events. The following describes in more detail the structure and function of the roof rollover assembly 10 according to the invention, with particular consideration of its structural design and its behavior in a vehicle rollover event. The roof crossmember 20 is a central structural component of the roof rollover assembly 10 and performs several load-bearing functions. It mechanically couples the two crashbox profiles 30 and distributes local forces across the entire roof width. Furthermore, the roof crossmember 20 has a stabilizing function within the roof structure, as it acts as a transverse connection between the body pillars, counteracting deformation of the vehicle roof 95, particularly through lateral bending or torsion. This increases both the lateral and torsional stiffness of the vehicle cell, i.e., its resistance to lateral bending and twisting. In the event of an asymmetrical load, for example from a diagonal rollover, the roof cross member 20 contributes to deformation symmetry and to the controlled force transmission into both crashbox profiles 30. It thus not only performs a mechanical coupling function, but also distributes the load and stiffens the structure, supporting the effect of the crashbox profiles 30. The roof crossbeam 20 is preferably designed as an extruded aluminum hollow profile with a U- or box-shaped cross-section. Alternatively, welded or bonded hybrid beams with locally reinforced segments or integrated sensor structures are also conceivable. Within the scope of the present invention, the crashbox profile 30 is a profiled structural element that is capable of controlled and permanent plastic deformation under mechanical stress, particularly in the event of a vehicle rollover. The crashbox profile 30 primarily serves to absorb energy through irreversible structural deformation and therefore features a special cross-sectional geometry and material composition. It consists in particular of multi-cell, extruded aluminum hollow profiles whose wall thicknesses, geometry, and optionally integrated filling materials are tailored to the requirements regarding deformation behavior and force transmission. Through structural-mechanical optimization, the Crashbox profiles 30 can be designed to selectively trigger localized buckling and flexing mechanisms. This distinguishes them significantly from conventional connecting beams or reinforcement profiles, which are primarily designed for stiffness and the transmission of forces without structural failure. Within the scope of this application, dissipation is understood as the conversion of mechanical impact energy into irreversible plastic deformation work. Dissipation is achieved structurally through targeted folding, buckling, or local instabilities within the crashbox profiles 30 and is optionally supported by integrated damping materials 40, for example, in the form of aluminum foam. The aim is to prevent the introduced energy from being transmitted further, but rather to eliminate it in a controlled manner within the roof rollover assembly 10, i.e., to convert it into a non-recoverable deformation. The crashbox profiles 30 and the roof crossbeam 20 are preferably manufactured from aluminum alloys using extrusion. This process allows for both high dimensional accuracy and customized wall thickness profiles. Depending on the application, symmetrical or asymmetrical geometries with internal webs, ribs, or pre-defined folds can be provided for the profile cross-sections. The structural design of the roof crossbeam 20 and the crash box profiles 30 is carried out primarily using numerical simulation methods such as the finite element method (FEM). In FEM, the geometry of a component is divided into a large number of small, interconnected elements, on which the mechanical stresses, deformations, and forces are calculated. The FEM method allows for a high-resolution analysis of complex component geometries under realistic loading conditions. Within the scope of the present invention, the deformation behavior under combined bending and compressive stress, the connection points to the crashbox profiles 30, and the joining points on the roof structure are investigated and optimized. The FEM simulation can analyze the force-energy ratio in the event of a crash, predict the buckling and folding behavior of the roof rollover assembly 10 under compressive stress, minimize local stress concentrations, and investigate the interaction with filling materials. In addition to classical FEM methods, modern data-driven methods, such as AI-supported simulation approaches or optimization algorithms based on machine learning, can also be used. These enable, for example, the automated generation of variants of the roof rollover assembly 10 based on predefined target criteria such as mass, energy absorption, or installation space compatibility. Numerical simulation methods not only allow for the precise design of individual components, but also, and especially, their vehicle-specific adaptation. Both the roof crossmember 20 and the crashbox profiles 30 can be adapted in terms of dimensions, wall thickness, geometry, or material combination to the specific requirements of different vehicle models, for example, depending on body shape, number of seat rows, or installation position. This enables flexible system integration with optimized protective performance for different vehicle architectures even in early development phases. The roof rollover assembly 10 can be implemented in various configurations, in particular as a single module in the area of ​​the B-pillar 70 (e.g., in two-door vehicles), as a double module with an additional assembly in the area of ​​the C-pillars 80 (e.g., in SUVs), or in a combined design with a continuous roof longitudinal member between the two modules. In vehicles with an extended interior, especially with a third row of seats, the roof rollover assembly can also include an additional D-pillar group, resulting in a triple module arrangement. This serves to structurally reinforce the rear roof area and protect the rearmost passenger compartment. Besides extruded aluminum, hybrid materials such as CFRP / aluminum composite profiles or aluminum-steel composite solutions are also conceivable. The connection to the vehicle's body structure can be achieved by welding, bolting, or bonding. In a vehicle rollover event, the vehicle 90 undergoes a complex movement, typically consisting of several phases. In a first phase, the vehicle roof 95 makes contact with the ground in a defined direction of impact – usually laterally or diagonally. In a second phase, a rotation or rolling motion occurs, during which various roof segments successively make contact with the ground. In a third phase, secondary impact impulses can act on the roof structure, for example, through follow-up movements, dynamic rebound, or collisions with objects. In this scenario, the roof rollover assembly 10 according to the invention can absorb energy sequentially or in parallel. As shown in Figures 4a to 4c, the plastic deformation of the crashbox profiles 30 results in modulated, multi-stage energy absorption, which retains its protective effect even in the event of multiple impacts. Different types of vehicle rollovers can lead to specific load paths in the crashbox profiles 30 of a roof rollover assembly 10. The roof rollover assembly 10 according to the invention offers several significant advantages: - The targeted plastic deformability of the crash box profiles 30 ensures that the impact energy is absorbed directly and in a controlled manner in the roof area. This prevents critical loads from being transferred unfiltered into adjacent, less resilient body structures. - The roof rollover assembly 10 can be used individually, for example in the area of ​​the B-pillars 70, as well as in combination, for example with an additional roof rollover assembly 12 at the C-pillars 80. In addition, for certain vehicle designs, especially those with a third row of seats or an extended rear section, another roof rollover assembly can be provided in the area of ​​the D-pillars. This allows for vehicle-specific adaptation, for example with regard to the body structure, the seating arrangement, or the safety requirements. - For longer vehicles (e.g.,SUVs with three rows of seats can utilize two or more roof rollover assemblies 10, 12 across the vehicle's longitudinal axis as an integrated load-bearing system. The roof crossmember 20 distributes external moments and torsional forces, thereby increasing the overall structural stiffness in rollover scenarios with complex load paths. The design of the roof rollover assembly 10 is such that it can be integrated into existing body structures without requiring significant modifications to the outer roof contour. At the same time, it allows for flexible designs, for example, in extruded aluminum profiles, hybrid materials, or fiber-reinforced constructions, as well as various joining methods (welding, bolting, bonding). The modular design of the roof rollover assembly 10 also enables adaptation to different vehicle architectures.- Using numerical simulation methods, in particular the finite element method (FEM), as well as AI-supported optimization approaches, the structure of the roof rollover assembly 10 can be specifically adapted to vehicle-specific load scenarios. Based on this, the component geometry can be varied using computer simulations, for example, through multi-cell profile structures or graduated wall thicknesses. This allows different variants to be designed with precision and optimized with regard to energy absorption and installation space behavior. Reference sign 10 Roof rollover assembly 20 Roof cross member 30 Crash box profile 40 Damping material 70 B-pillar 80 C-pillar 90 Vehicle 95 Vehicle roof

Claims

Roof rollover assembly (10) for a vehicle (90), comprising a roof crossmember (20) arranged in the roof area of ​​the vehicle (90) and extending transversely to the direction of travel between the opposite sides of the vehicle, two crashbox profiles (30) each connected at one end to the roof crossmember (20) and having a force-conducting connection to a B-pillar (70) and / or a C-pillar (80) and / or a D-pillar, wherein the crashbox profiles (30) are designed as extruded, multi-cell hollow profiles made of aluminum, wherein the crashbox profiles (30) are provided with a damping material (40), wherein the crashbox profiles (30) have locally defined deformation zones with targeted wall thickness reduction or integrated predetermined buckling points, wherein the connection between the roof crossmember (20) and the crashbox profiles (30) is designed such that occurring forces are directed into the crashbox profiles (30) in a controlled manner. become,and wherein the crashbox profiles (30) are designed such that they are plastically deformable in the event of a vehicle rollover to absorb and dissipate impact energy, wherein, in the event of a vehicle rollover, rollover forces acting on the roof crossmember (20) are directed into the crashbox profiles (30) and are dissipated there by plastic deformation of the crashbox profiles (30) and by the damping material (40) within the roof rollover assembly (10) before the forces are transmitted via the respective body pillar into the vehicle body. Roof rollover assembly (10) according to claim 1, wherein the roof cross member (20) is designed as a closed rectangular cross-section, U-profile or hybrid profile, in particular as an aluminum extrusion profile or in mixed construction with fiber-reinforced plastics. Roof rollover assembly (10) according to claim 1 or 2, wherein the connection between the roof cross member (20) and the crash box profiles (30) is form-fit or material-fit, in particular by screwing, welding or adhesive bonding. Roof rollover assembly (10) according to one of the preceding claims, wherein the structural design of the roof rollover assembly (10) is carried out by means of numerical simulation, in particular by means of finite element method (FEM), wherein the deformation behavior under combined bending and compressive load is analyzed, and wherein the simulation includes the optimization of the force-energy ratio, the prediction of the buckling behavior and the reduction of local stress peaks. Roof rollover assembly (10) according to claim 4, wherein the simulation is supplemented by AI-supported optimization methods for the creation of variants with regard to cross-sectional geometry, wall thickness or material distribution. Roof rollover assembly (10) according to one of the preceding claims, wherein the roof rollover assembly (10) is modular and can be arranged at different positions along the longitudinal roof axis of a vehicle (90) in the area of ​​the B-pillars (70) and / or C-pillars (80) and / or D-pillars.

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