Frame element of a motor vehicle and motor vehicle

Abstract

Frame element for a motor vehicle, with an extruded profile (32) which defines several chambers (381, 382, ​​383, 384), wherein two adjacent chambers (381, 382, ​​383, 384) are separated from each other by a web (361, 362, 363), wherein two spaced-apart webs (361, 362, 363) have different curvatures, wherein the curvatures of the webs (361, 362, 363) are designed such that a predefined crash-related forming behavior of the extruded profile (32) is achieved.

Description

The invention relates to a frame element for a motor vehicle, comprising an extruded profile which defines several chambers, wherein two adjacent chambers are separated from each other by a web. Such frame elements for a motor vehicle are generally known from the prior art, wherein the frame elements comprise a hollow body formed as an extruded profile, with a circumferential wall of the extruded profile radially delimiting a cavity. The end faces of the frame element can be open or closed. Webs typically extend through the cavity, dividing it into several chambers. The webs usually have a straight shape. Alternatively, the webs can also have a curved shape. A frame element of a motor vehicle is disclosed, for example, in EP 4 386 952 A1, wherein all webs are identical and have a straight or curved cross-section. Such frame elements serve, among other things, to absorb loads during a crash and thus dampen the impact forces by deforming and partially absorbing the crash energy. This deformation can occur when the frame element folds or buckles under the influence of an external object at a specific load point. It is advantageous if the deformation during a crash is predictable and predefined at each load point. The object of the invention is therefore to provide a frame element of a motor vehicle through which the crash loads can be predictably absorbed and selectively dampened. The problem is solved by the features of claim 1. According to the invention, two spaced-apart webs have different curvatures, the curvatures of the webs being designed such that a predefined, crash-induced deformation behavior of the extruded profile is achieved. Different curvatures also include the possibility that one web is straight, i.e., without any curvature, and another web is curved. The webs are arranged at different positions on the frame element and each separates two adjacent chambers. The webs can be spaced apart from each other, particularly in the vehicle's vertical, transverse, or longitudinal direction. Because the webs have different curvatures, the stiffness of the frame element is adjusted in certain areas such that a predefined deformation, in particular a predefined buckling or folding behavior of the frame element, occurs under a crash load. In a crash-induced load on the frame element, the webs are subjected to compressive stress, whereby the compressive stress required to buckle the webs depends on their curvature. As the curvature of the web increases, i.e., as the radius of the curvature decreases, the required compressive stress that leads to buckling decreases. Because the webs have different curvatures, one web buckles before the other, and as soon as one web buckles, the extruded profile, and thus the entire frame element, buckles in the area of ​​the buckled web, causing the frame element to fold. This deformation behavior occurs almost independently of the load position and / or the design of the motor vehicle, i.e., independently of any counterforce present in a crash from another vehicle component. This provides a space-saving frame element that exhibits predictable, predefined deformation behavior under crash loads, reliably absorbing and dampening the impact forces. No additional elements are required to achieve this predefined deformation behavior of the frame element under crash loads. Because the frame element has an extruded profile, or is formed by an extruded profile, it can be manufactured simply and cost-effectively. The extruded profile is, in particular, an aluminum extrusion profile. Preferably, at least one web with a straight shape and at least one web with a curved shape are provided. A straight web has no curvature, so that, according to the invention, the straight web and the curved web have different curvatures. The straight web requires a high compressive load to buckle, whereas the curved web buckles even under a lower compressive load than the straight web. Thus, the stiffness of the frame element is higher in the area of ​​the straight web than in the area of ​​the curved or bent web, so that the area of ​​the curved web forms a predetermined buckling zone. Alternatively, two curved webs can be provided, wherein the two webs have different curvatures, with the area of ​​the web with the greater curvature forming the predetermined buckling zone. In a preferred embodiment, the extruded profile has an L-shaped cross-section, with a straight web in a transition area between two leg sections and a curved web in at least one of the leg sections. This gives the transition area a higher stiffness compared to the leg section. Under crash-induced loading of the frame element, the curved web buckles ahead of the straight web, regardless of the load position. This causes the frame element to always buckle and fold in a predefined manner at the area of ​​the curved web. During folding, the two leg sections move towards each other. Thus, a predefined deformation behavior occurs under every crash-induced loading of the frame element. The problem is also solved by a motor vehicle which has a frame element according to one of claims 1 to 4. The frame element is in particular part of a battery frame or a body-in-white support. An embodiment of the invention is explained in more detail with reference to the drawings. Fig. 1 schematically shows a motor vehicle, and Fig. 2 shows a section of the motor vehicle from Fig. 1 in cross-section. Fig. 1 shows a motor vehicle 10, which is designed as an electric vehicle 11. The electric vehicle 11 comprises an electric drive unit 12 for propulsion, which drives two vehicle wheels assigned to a common axle, a control unit 14, and a traction battery 20 designed as an underfloor battery. The control unit 14 is electrically connected between the electric drive unit 12 and the traction battery 20, so that the electric drive unit 12 can be supplied with the electrical energy provided by the traction battery 20 via the control unit 14. The traction battery 20 is surrounded in the longitudinal and transverse directions of the vehicle by a battery frame 30 in order to reduce the risk of damage to the traction battery 20 in a crash, i.e., a side impact or a frontal impact.The battery frame 30 comprises two lateral frame elements 31 extending longitudinally along the vehicle, and two frame elements 33 extending transversely along the vehicle. The frame elements 33 connect the two lateral frame elements 31 to each other at two different end regions, thus forming a circumferential battery frame 30. All frame elements 31 are made of extruded profiles. Fig. 2 shows a section of the traction battery 20 and the battery frame 30, i.e., the frame element 31. A lower cover element 40, for example an underbody protection plate, is arranged below the traction battery 20. An upper cover element 42 is arranged above the traction battery 20. The upper cover element 42 and the lower cover element 40, together with the battery frame 30, define a battery compartment 44 in which the traction battery 20 is arranged. The frame elements 31 each have an extruded profile 32 with an L-shaped cross-section. The L-shaped extruded profile 32 forms a circumferential boundary of a cavity 34, through which several webs 361, 362, 363 extend. The webs 361, 362, 363 divide the cavity 34 into several chambers 381, 382, ​​383, 384, wherein a first web 361 separates a first chamber 381 and a second chamber 382, ​​a second web 362 separates the second chamber 382 and a third chamber 383, and a third web 363 separates the third chamber 383 from a fourth chamber 384. The first web 361 and the third web 363 are curved. The second web 362 is straight. In a crash event caused by a crash load FB as shown in Fig. 2, the frame element 30 folds according to a folding direction FR shown in Fig. 2. This deformation behavior occurs due to the design of the webs 361, 362, 363. All webs 361, 362, 363 are subjected to a compressive load during a crash load FB. The second, straight web 362 only buckles under a high compressive load, while the first curved web 361 and the third, curved web 363 buckle under a compressive load lower than that of the straight web 361. Due to this design of the webs 361, 362, 363, the transition area of ​​the frame element 30, in which the straight, second web 362 is arranged, has a higher stiffness compared to the leg areas in which the curved webs 361, 363 are arranged, so that the walls of the extruded profile 32 in the leg areas, i.e.The webs 361 and 363 initially deform. In contrast, the transmission area, i.e., the area in which the straight web 362 is located, does not deform at all, or only under a higher load. This causes the frame element 30 to fold in the folding direction FR around its stiffest point, i.e., around the transition area. Such folding of the frame element 30 occurs almost independently of the position at which the crash load acts on the frame element 30, since the webs are subjected to compression regardless of the load position, i.e., regardless of the force application position of the crash load FB, and the webs 361 and 363 buckle before the web 362. This provides a frame element 31 which exhibits a predictable, predefined deformation behavior under crash-related load and thus reliably absorbs and dampens the crash load in the event of a crash. QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature EP 4 386 952 A1

[0002]

Claims

Frame element for a motor vehicle, with an extruded profile (32) which defines several chambers (381, 382, ​​383, 384), wherein two adjacent chambers (381, 382, ​​383, 384) are separated from each other by a web (361, 362, 363), characterized in that two spaced-apart webs (361, 362, 363) have different curvatures, wherein the curvatures of the webs (361, 362, 363) are designed such that a predefined crash-related forming behavior of the extruded profile (32) is achieved. Frame element according to claim 1, characterized in that at least one web (362) with a straight shape and at least one web (361, 363) with a curved shape are present. Frame element according to claim 1 or 2, characterized in that a predefined, crash-induced forming behavior is established on the extruded profile (32) independently of the crash-induced load position. Frame element according to one of the preceding claims, characterized in that the extruded profile (32) has an L-shaped cross-section, wherein in a transition area between two leg regions a straight web (362) is present and at least in one of the leg regions a web (361, 363) with a curved shape is present. Motor vehicle with a frame element (30) according to one of claims 1 to 4. Motor vehicle according to claim 5, characterized in that the frame element (30) is part of a battery frame or a body shell support.

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