longitudinal beam

Abstract

Longitudinal beam (2) for a vehicle, having a longitudinal axis (16) that is to be arranged parallel to a forward direction of travel of the vehicle, wherein the longitudinal beam (2) has along the longitudinal axis (16) a front section (8), a rear section (10) which form a front part (4) of the longitudinal beam (2), and a rear part (6), wherein at least one front predetermined bending point (12a, 12b) is arranged in a front transition between the two sections (8, 10) and at least one rear predetermined bending point (14) is arranged in a rear transition between the rear section (10) and the rear part (6), wherein the predetermined bending points (12a, 12b, 14) are deformed upon impact of the vehicle, with the front transition moving downwards and the rear transition moving upwards, characterized in that the rear part (6) has a higher modulus of elasticity and / or shear modulus than the front part (4).wherein the front part (4) is more easily deformable than the rear part (6).

Description

The invention relates to a longitudinal beam for a vehicle according to the preamble of claim 1 and a vehicle. In a head-on collision, a vehicle is abruptly decelerated, causing the rear of the vehicle to continue moving due to its inertia, while the front of the vehicle remains stationary. From the occupant's perspective, this results in the front of the vehicle tilting downwards. Consequently, an unsuspecting occupant is thrown upwards relative to the front of the vehicle, causing their head to strike a roof frame or window, particularly the windshield. DE 10 2006 036 902 A1 describes a structural element for a motor vehicle body. A crash structure for a vehicle is known from DE 10 2013 020 837 B3. A subframe designed as an axle carrier for a vehicle, comprising two longitudinal beams and a stiffening structure arranged between the two longitudinal beams, is known from the generic designation WO 2013 / 064 270 A1. The longitudinal beams are essentially designed as hollow profiles and have at least one predetermined buckling point in the form of a curvature extending in the longitudinal direction of the longitudinal beams. A rear vehicle body structure of a motor vehicle known from DE 20 2015 008 170 U1 comprises a rear floor plate and a pair of right and left rear side frames, which extend essentially in a longitudinal direction of the vehicle and are connected to both side sections in a width direction of the rear floor plate. US patent 2017 / 057548A1 describes a body structure for the rear of a vehicle with a left rear frame consisting of a lower and an upper section, the lower section being thicker than the upper section. Furthermore, the left rear frame is divided into three zones of varying softness. A motor vehicle body known from DE 10 2019 105 646 A1 with a body structure has at least one longitudinal beam arrangement in a front area of ​​the motor vehicle body, which is provided with a crash box as a deformable structural component in or on its front end section. DE 10 2018 000 499 A1 describes a body structure of a motor vehicle with a front axle carrier which has at least one front axle longitudinal member, wherein the front axle longitudinal member is fixed to a body shell longitudinal member of a body shell. Against this background, improving the safety of vehicle occupants was a task. This problem is solved by a longitudinal beam and a vehicle with the features of independent claims 1 and 6. Embodiments of the longitudinal beam and the vehicle are described in the dependent claims and the description. The longitudinal member according to the invention is designed for a vehicle, e.g., a motor vehicle, and has a longitudinal axis that is originally to be arranged, can be arranged, and / or aligned parallel to a forward direction of travel of the vehicle. The longitudinal member has a front section and a rear section along its longitudinal axis, both of which form a front part of the longitudinal member, and a rear part. At least one front predetermined bending point is arranged in a front transition between the two sections of the front part, and at least one rear predetermined bending point is arranged in a rear transition between the rear section of the front part and the rear part. In a typical frontal impact of the vehicle, at least the predetermined bending points, and generally all of them, are deformed.deformed, whereby the front transition is moved downwards with respect to its original orientation relative to the longitudinal axis and the rear transition is moved upwards with respect to its original orientation relative to the longitudinal axis, e.g. along a vertical axis of the vehicle perpendicular to the longitudinal axis or forward direction of travel, e.g. shifted and / or lifted. The front part is softer than the rear part. The rear part has a higher modulus of elasticity and / or shear modulus than the front part. Consequently, the front part is more easily deformed or deformed than the rear part due to a force acting upon it. Upon impact, a force acts on the longitudinal member, deforming both parts, with the front part deforming more than the rear part. It is also optionally possible for the front section to be more easily deformed than the rear section and thus deform more upon impact. In its embodiment, the longitudinal beam has an upper front predetermined buckling point on and / or on an upper side, e.g., an upper chord, and a lower front predetermined buckling point on and / or on a lower side, e.g., a lower chord. Furthermore, the longitudinal beam has an upper rear predetermined buckling point in its design at the rear transition and / or on the upper side, e.g. the top chord. In this configuration, the longitudinal beam is formed in one piece, for example as an extruded profile, with both parts made of aluminum, usually aluminum alloys. The two parts are made of different aluminum alloys, with the aluminum alloy of the front part being more easily deformed than that of the rear part and thus deforming more upon impact. It is also possible for the rear part to be made of steel, for example, a steel sheet and / or steel profile, which is typically rigidly connected to the front part. It is also possible that at least one, and usually all, of the intended bending points are designed as a rib or ribs. In this configuration, the intended bending point in the rear transition is larger than each of the intended bending points in the front transition. Furthermore, it is possible that the front transition with its two intended bending points is more easily deformed than the rear transition with its at least one intended bending point and is therefore deformed more upon impact. In a further embodiment, at least the rear part of the longitudinal member is designed to push upwards at least one front area of ​​the vehicle's roof, which is connected in its front area to a windshield of the vehicle, when the rear part is moved upwards, e.g. lifted, due to deformation of the longitudinal member as a result of the impact. The longitudinal member is typically designed as a component of the vehicle's chassis or frame, with the chassis comprising several, usually two, such longitudinal members and several, usually two, cross members. The chassis is designed to support the vehicle's powertrain and body, which also includes the roof. Each longitudinal member, for example, its front end, is connected at the front to a front cross member via a connecting element. Furthermore, each longitudinal member, for example, its rear end, is connected at the rear to a rear cross member via another connecting element. The vehicle according to the invention, e.g. motor vehicle, has at least one longitudinal member shown above, which is arranged parallel to a forward direction of travel of the vehicle. During the manufacture of the vehicle, at least one longitudinal beam, e.g. an embodiment of the longitudinal beam described above, is arranged in it, e.g. in a body shell of the vehicle, with a continuous longitudinal axis, wherein the longitudinal axis is originally oriented or aligned parallel to an intended forward direction of travel of the vehicle. If, during operation, the vehicle is subjected to a typically frontal impact with an obstacle, at least the designed articulation points are deformed, for example, compressed and / or pressed together parallel to the forward direction of travel or the longitudinal axis. In this process, the front transition is moved downwards relative to its original orientation of the longitudinal axis, and the rear transition is moved upwards relative to its original orientation of the longitudinal axis, for example, raised. Upon impact, a force parallel to the forward direction of travel, and thus parallel to the longitudinal axis, acts on the longitudinal member, deforming the designed buckling points, for example, by compressing them parallel to the force. It is possible that the front section, the rear section, and the rear section each have their own partial longitudinal axis, which originally aligned one behind the other, forming the longitudinal axis of the longitudinal member. Due to deformation of the designed buckling points by the force acting on the longitudinal member, the partial longitudinal axis of the front section buckles upwards, the partial longitudinal axis of the rear section buckles downwards, and the partial longitudinal axis of the rear section buckles upwards, with each pair of immediately adjacent partial longitudinal axes being arranged and / or oriented at an obtuse angle relative to each other. Furthermore, at least a front section of the vehicle's roof is moved vertically upwards, parallel to the vehicle's vertical axis, due to a vertical movement (e.g., displacement) of the rear section of the front part, the rear transition, and / or the rear part upwards, or, in some configurations, due to a complete deformation of the longitudinal member. Typically, the vehicle has a horizontal plane in which the longitudinal axis of the longitudinal member lies, with the vehicle's vertical axis being oriented perpendicular to this plane and having the same direction as a normal vector to the plane. If the vehicle impacts the obstacle, the front transition is moved vertically downwards, largely perpendicular to the plane, and the rear transition is moved vertically upwards, largely perpendicular to the plane.The vehicle frame comprises at least one longitudinal beam and at least one transverse beam with a transverse axis oriented perpendicular to the longitudinal axis of the longitudinal beam, wherein the longitudinal axis and the transverse axis lie in the plane of the vehicle. The longitudinal member is located in the front of the vehicle and comprises at least the front and rear sections, which are arranged one behind the other in the direction of travel, usually in the forward direction. Furthermore, the front section has a front and a rear section, between the front transition of which the two front predetermined bending points are formed and / or arranged. At least one rear predetermined bending point is located in the rear transition between the front and rear sections. The predetermined bending points in the two transitions ensure, among other things, that in the event of an impact, the rear section of the front section pushes the rear section upwards. The innovative buckling behavior of the longitudinal beam (LTR) is designed to protect unbelted or unseaten occupants of the vehicle in the event of a collision. It is further stipulated that, to protect, for example, an unbelted occupant in a crash, the vehicle will ride up or rise upon a frontal impact with the obstacle, with the unbelted occupant falling into an airbag. In this configuration, the longitudinal member (LTR) of the body, in the rear section of the front section, typically at the transition between the front and rear sections, bends upwards at an obtuse angle in a V-shape. The transition between the front and rear sections of the front section, however, bends downwards. At least the front section of the multi-part longitudinal member is formed from an extruded aluminum profile. For the intended optimized bending behavior of the longitudinal member, one or more ribs are incorporated into an upper and a lower flange as predetermined bending points. This causes the extruded profile to bend at specified positions, downwards at the front transition and upwards at the rear transition, causing the rear section of the longitudinal member to ride up and / or bend upwards. The buckling behavior incorporated into the longitudinal beam causes the vehicle's front end to tilt upwards upon impact with an obstacle, rather than downwards. This protects the unbuckled occupant from impact with the roof, such as a roof frame. In the event of a collision, the longitudinal beam protects the unbuckled occupant, for example, through the upward movement of the vehicle's front end. This upward movement is specifically induced by the buckling behavior of the longitudinal beam, or at least its transitions. The invention is schematically illustrated with reference to embodiments in the drawing and is described schematically and in detail with reference to the drawing. Figures 1a and 1b show a schematic representation of an embodiment of the longitudinal beam according to the invention during operation of an embodiment of the vehicle according to the invention. Figure 2a shows the effects of the prior art in the event of an impact of the vehicle on an obstacle. Figure 2b shows the effects of the embodiment on the vehicle. The figures are described in a coherent and comprehensive manner. The same reference symbols are assigned to the same components. The embodiment of the longitudinal member 2 according to the invention, schematically depicted in different states in Figs. 1a and 1b, is intended and / or designed for the embodiment of the vehicle according to the invention, here, for example, for a motor vehicle. The longitudinal member 2 installed in the vehicle comprises as components a front part 4 and a rear part 6, wherein the front part 4 further comprises a front section 8 and a rear section 10. At a transition or boundary between the front and rear sections 8, 10, two front predetermined bending points 12a, 12b, which are here described as corrugations, are arranged. An upper front predetermined bending point 12a is located on and / or at an upper side, here a top flange, and a lower front predetermined bending point 12b is located on and / or at a lower side, here a bottom flange, of the longitudinal beam 2. Both front predetermined bending points 12a, 12b are arranged vertically one above the other and have the same dimensions. The two front predetermined bending points 12a, 12b form a so-called corrugation pattern. The front part 4 and the two sections 8, 10 are made of aluminum or an aluminum alloy, here an extruded profile. The rear part 6 is also made of an extruded profile and is further made of aluminum or a harder metal, e.g., steel.The rear transition, including the rear predetermined bending point 14, is usually made of aluminum, e.g., an aluminum alloy. Furthermore, at a transition or boundary between the rear section 10 of the front part 4 and the rear part 6, a further rear buckling point 14, designed or to be described as a corrugation, is arranged on and / or on an upper side, here the top flange, of the longitudinal beam 2, wherein this rear buckling point 14 has a larger dimension than either of the two front buckling points 12a, 12b. Alternatively, it is possible that all buckling points 12a, 12b, 14 are of the same size, or that the rear buckling point 14 is smaller than at least one of the front buckling points 12, 12b, which may be of different sizes depending on the embodiment, such that the upper front buckling point 12a is larger than the lower front buckling point 12b or vice versa. Figures 1a and 1b each show a longitudinal axis 16 of the longitudinal member 2, which is oriented horizontally and parallel to the forward direction of travel of the vehicle. The longitudinal axis 16 lies in a plane of the vehicle, with a vertically oriented vertical axis of the vehicle perpendicular to this plane. In the forward direction of travel, the front section 8 is located in front of the front transition with the two front predetermined bending points 12a, 12b, which is located in front of the rear section 10, which is located in front of the rear transition with the rear predetermined bending point 14, which in turn is located in front of the rear section 6. When the vehicle is operated with a longitudinal beam 2 installed in it, it is intended that this beam is originally straight, e.g. completely intact, as shown in Fig. 1a. If the front of the vehicle collides with an obstacle, the longitudinal member 2 is deliberately deformed, as shown in Fig. 1b. This deformation is described by a kink line 18, which is also shown in Fig. 1b. Fig. 1b shows a first partial longitudinal axis 22a of the front section 8, a second partial longitudinal axis 22b of the rear section 10, and a third partial longitudinal axis 22c of the rear section 6, which together form the kink line 18. The two front predetermined bending points 12a, 12b are pressed in, whereby the transition between the front and rear sections 8, 10, which has the two front predetermined bending points 12a, 12b, is shifted downwards with respect to the longitudinal axis 16, whereby the two sections 8, 10 of the front part 4 or their partial longitudinal axes 22a, 22b are bent at an obtuse angle relative to each other, whereby the transition between the two sections 8, 10 is bent concavely from a top-down perspective, when viewed from above, on the longitudinal beam 2. The front section 8 is shifted vertically upwards and / or bent with respect to the vehicle plane. Furthermore, the rear predetermined bending point 14 is pressed in, whereby the rear transition between the rear area 10 of the front part 4 and the rear part 6, which has the rear predetermined bending point 14, is shifted upwards with respect to the longitudinal axis 16, whereby the rear area 10 of the front part 4 or its partial longitudinal axis 22b and the rear part 6 or its partial longitudinal axis 22c are bent here at an obtuse angle relative to each other, whereby the transition between the rear areas 10 of the front part 4 and the rear part 6 is bent convexly from a perspective from above, when looking down at the longitudinal member 2, whereby the rear part 6 is shifted vertically upwards and / or bent with respect to the vehicle plane, which is indicated here by an arrow 20. Upon impact, the front end of the front section 8 of the front part 4 of the longitudinal member 2 is moved upwards. Conversely, the front transition between the front and rear sections 8, 10 of the front part 4 of the longitudinal member 2, and thus also the two front predetermined bending points 12a, 12b, is / are moved downwards. Furthermore, the rear transition between the rear section 10 of the front part 4 and the rear part 6 is moved upwards, and the rear predetermined bending point 14 is also moved upwards. The effects of the prior art on the impact of the vehicle on the obstacle are schematically illustrated in Fig. 2a. In contrast, the effect of the embodiment of the longitudinal beam 2 on the vehicle is schematically illustrated in Fig. 2b. Figures 2a and 2b schematically depict a windshield 30 and a roof of the vehicle in an initial position 32a. An occupant, here a driver or passenger, is seated in the front seat of the vehicle, and their head 24 is schematically shown. Upon impact, the head 24 is moved forward in the direction of arrow 36. In the prior art (Fig. 2b), this results in a collision 38 of the head 34 with the roof 32a and / or the windshield 30. However, if the vehicle has the embodiment of the longitudinal member 2 presented here, the defined and / or targeted deformation of the longitudinal member 2 described above results in the front of the vehicle and / or the front section of the vehicle being shifted upwards, whereby the roof is also shifted upwards from the initial position 32a to an end position 32b. This upward shift of the roof results from an upward shift of the rear section 6 and / or, if applicable, the front section 8 of the front section 4. This prevents the head 34 from dangerously impacting the roof or the windshield 30. The upward movement of the roof provides sufficient clearance for the occupant's head 34, thus preventing contact between the head 34 and the roof. Furthermore, this also prevents injuries to the occupant's head 34 and neck. REFERENCE MARK: 2 Longitudinal beam 4 Front section 6 Rear section 8 Front area 10 Rear area 12a, 12b Front predetermined bending point 14 Rear predetermined bending point 16 Longitudinal axis 18 Bend line 20 Arrow 22a, 22b, 22c Partial longitudinal axis 30 Windscreen 32a Initial position 32b Final position 34 Head 36 Arrow 38 Collision 40 Arrow

Claims

Longitudinal beam (2) for a vehicle, having a longitudinal axis (16) that is to be arranged parallel to a forward direction of travel of the vehicle, wherein the longitudinal beam (2) has along the longitudinal axis (16) a front section (8), a rear section (10) which form a front part (4) of the longitudinal beam (2), and a rear part (6), wherein at least one front predetermined bending point (12a, 12b) is arranged in a front transition between the two sections (8, 10) and at least one rear predetermined bending point (14) is arranged in a rear transition between the rear section (10) and the rear part (6), wherein the predetermined bending points (12a, 12b, 14) are deformed upon impact of the vehicle, with the front transition moving downwards and the rear transition moving upwards, characterized in that the rear part (6) has a higher modulus of elasticity and / or shear modulus than the front part (4).where the front part (4) is more easily deformable than the rear part (6). Longitudinal beam (2) according to claim 1, characterized in that the longitudinal beam (2) has an upper front predetermined bending point (12a) on an upper side and a lower front predetermined bending point (12b) on a lower side in the front transition. Longitudinal beam (2) according to claim 1 or 2, characterized in that the longitudinal beam (2) has an upper rear predetermined bending point (14) on an upper side at the rear transition. Longitudinal beam (2) according to one of the preceding claims, characterized in that at least one predetermined buckling point (12a, 12b, 14) is formed as a bead. Longitudinal member (2) according to one of the preceding claims, characterized in that the rear part (6) is designed to move at least a front area of ​​a roof of the vehicle upwards when the rear part (6) is moved upwards during the impact. Vehicle characterized by at least one longitudinal member (2) according to one of the preceding claims, which is arranged parallel to a forward direction of travel of the vehicle.

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