Body structure for a two-track vehicle

Abstract

Body structure for a two-track vehicle, with a subframe (1) for a vehicle rear axle, wherein the subframe (1) is connected to the vehicle body (17) via a bolted connection point (S), wherein the subframe (1) is connected to the vehicle body (17) via at least one subframe bearing (15), which subframe bearing (15) is composed of a subframe-side bearing component (27) and a body-side bearing component (29), between which a vibration damping unit (31) is arranged, wherein the body-side bearing component (29) of the subframe bearing (15) is connected to the vehicle body (17) via the bolted connection point (S), characterized in that the body structure has at least one protective element (46) on the rear-crash-facing side of the bolted connection point (S), which is connected to the vehicle body (17) via the bolted connection point (S),and that the screw connection point (S) has a screw bolt (33) with which both the body-side bearing component (29) of the subframe bearing (15) and the protective element (46) are screwed to the vehicle body (17), and that in a rear-end collision the protective element (46) and the screw connection point (S) are integrated into a load path (L) via which the introduced impact forces (F, A ) can be transmitted from the protective element (46) to the vehicle body (17).

Description

[0001] The invention relates to a body structure for a two-track vehicle according to the preamble of patent claim 1.

[0002] In an electrically powered vehicle, the rear wheels can be driven by at least one electric motor. The electric motor can be supported by a rear axle carrier or a rear subframe, to which the wheel control arms of the wheel suspension for the rear wheels are laterally pivoted. The traction battery used to supply power to the electric motor can be installed in the vehicle in front of the rear subframe in the direction of travel, for example, in the underbody of the vehicle.

[0003] For full use of the available installation space, it is preferable for the traction battery to be positioned as close as possible to the axle carrier, allowing the traction battery to maximize its volume. However, for crash safety reasons, it is essential that the traction battery is not damaged by deforming the body and chassis structure and / or the axle carrier in the event of a rear-end collision. The above applies not only to the traction battery, but generally to any other crash-sensitive functional component installed directly in front of the rear subframe in the direction of travel.

[0004] DE 199 012 99 C1 discloses a generic body structure for a two-track vehicle, in which the subframe is bolted to the vehicle body at a screw connection point via a subframe bearing. The subframe bearing consists of a radially outer bearing sleeve and a radially inner bearing sleeve, between which an elastomer body is vulcanized. A screw bolt is guided through the radially inner bearing sleeve in the vertical direction of the vehicle, rigidly clamping the inner bearing sleeve to the vehicle body. The radially outer bearing sleeve, in contrast, is elastically and flexibly connected to the body-side inner bearing sleeve via the elastomer body and mounted in a subframe bearing eye.In addition, a stop disc is clamped between the screw head of the screw bolt and a front side of the inner bearing sleeve facing away from the vehicle body, which limits the axial stroke movement of the outer bearing sleeve.

[0005] In a rear-end collision, a rear body structure, such as a spare wheel well, undergoes plastic deformation as crash energy is dissipated and pressed into contact with the rear subframe mounts. In the event of significant impact forces, the subframe mount is loaded in the vehicle's longitudinal direction, i.e., transverse to its axial direction, to a block dimension. As the crash progresses, this results in the bolt aligned vertically in the vehicle being subjected to high shear forces, causing it to fracture prematurely. A rear subframe mount destroyed in this way results in the rear subframe being pushed against the aforementioned functional component, such as the traction battery, with high residual acceleration, potentially damaging the subframe longitudinal members, the traction battery, or its power electronics.

[0006] DE 198 30 026 A1 discloses a supporting structure for a motor vehicle. DE 10 2012 024 145 A1 discloses a protective device for a passenger car. DE 37 01 723 A1 discloses an impact protection device. DE 603 ​​09 846 T2 discloses a frame structure for a motor vehicle and a protective part. DE 10 2012 204 032 A1 discloses a front wheel suspension on a two-track vehicle. DE 10 2005 053 875 A1 discloses a screw connection between a bearing of a subframe and a tubular support of the body of a motor vehicle.

[0007] The object of the invention is to provide a body structure for a two-track motor vehicle in which a crash-sensitive functional unit, which is installed directly in front of the rear subframe, is protected in a simple manner from damage caused by a rear crash.

[0008] The object is solved by the features of patent claim 1. Preferred developments of the invention are disclosed in the subclaims.

[0009] According to the characterizing part of patent claim 1, at least one protective element is assigned to the subframe mount, which is connected to the vehicle body in a force-transmitting manner via the screw connection point at which the subframe mount is connected to the vehicle body. The protective element is arranged on the side of the subframe mount facing the rear crash. In the event of a rear crash, the protective element can be deformed, dissipating crash energy. The protective element and the above-mentioned screw connection point between the subframe mount and the vehicle body are integrated into an additional load path, via which the impact forces introduced can be transmitted from the protective element to the vehicle body.

[0010] The additional load path reduces early crash-related loading of the rear subframe mounts, thereby reducing the risk of premature damage to the rear subframe mounts. Furthermore, the additional load path is decoupled from the vibration damping unit (in particular, an elastomer body) located between the two mount components, i.e., the inner and outer bearing sleeves. This prevents the subframe mount from being loaded to a block dimension in the vehicle's longitudinal direction at an early point in the crash, which can lead to disadvantageously high shear stress at the bolted connection point. The bolted connection point features a screw bolt that performs a dual function of clamping both the inner bearing sleeve and the protective element to the vehicle body.

[0011] The invention is applicable to a connection of the subframe to the vehicle body with the interposition of a subframe bearing. Such a subframe bearing is constructed from a subframe-side bearing component, in particular a radially outer bearing sleeve, and a body-side bearing component, in particular a radially inner bearing core. A vibration damping unit, in particular consisting of an elastomer body and / or hydraulically interconnected working and compensation chambers, is arranged between the two bearing components. The body-side bearing component of the subframe bearing is connected to the vehicle body via the above-mentioned screw connection point.

[0012] The invention is described above and below with reference to a specific embodiment in which the subframe bearing is constructed from an outer bearing sleeve and an inner bearing sleeve, with an elastomer body vulcanized between them. The radially outer bearing sleeve of such a subframe bearing is pressed into a corresponding subframe bearing eye, which is preferably formed from the same material and / or integrally on the subframe. Alternatively, however, any other embodiments of subframe bearings are also intended to be encompassed by the invention, which are generally constructed from a body-side bearing component, a subframe-side bearing component, and an intermediate vibration damping unit.According to the invention, the only decisive factor is that the screw connection point between the subframe bearing and the vehicle body is also used in a dual function to connect the protective element, so that the protective element and the screw connection point are components of the above load path that forms in the event of a rear-end crash.

[0013] As mentioned above, the screw bolt is guided through the hollow cylindrical inner bearing sleeve at the screw connection point, allowing the inner bearing sleeve, together with the protective element, to be rigidly clamped to the vehicle body. To ensure easy mounting of the subframe during normal driving, it is advantageous if the screw axis of the screw bolt, i.e., its center axis, is aligned with the vehicle's vertical direction, i.e., transverse to the impact forces introduced in the event of a rear-end crash. The radially outer bearing sleeve, on the other hand, is not rigidly connected to the vehicle body, but rather is elastically and flexibly connected to the radially inner, body-side bearing sleeve via the elastomer body.

[0014] A subframe bearing designed in this way can have at least one stop disc which interacts with the outer bearing sleeve and / or with the elastomer body in order to limit axial and / or radial movement between the radially inner and outer bearing sleeves during normal driving operation.

[0015] In a design variant with fewer components, the stop plate can also serve a dual function as a protective element. In particular, the protective element and the stop plate can be constructed from the same material and / or in one piece as a single structural unit, which is clamped together by means of the screw bolt. Alternatively, however, the protective element can also be constructed from the same material and / or in one piece with the screw bolt, particularly at its bolt head.

[0016] In one technical implementation of the invention, the protective element is spaced rearward from the subframe bearing in the vehicle's longitudinal direction by a deformation clearance. The outer bearing sleeve of the subframe bearing can be mounted or pressed into a bearing eye of the subframe. In this case, the deformation clearance is defined in the vehicle's longitudinal direction between the protective element and the subframe bearing eye.

[0017] To effectively dissipate crash energy in the event of a rear-end collision, it is preferable to design the protective element as a deformation element. In this case, in a rear-end collision, the protective element only comes into contact with the subframe bearing eyelet once the aforementioned deformation clearance has been exhausted and after plastic deformation has occurred, thereby transferring the impact forces into the outer bearing sleeve. By providing the protective element, the impact forces are transferred to the outer bearing sleeve at a later point in the crash compared to the above-mentioned prior art.

[0018] In a simple manufacturing implementation, the stop disk and the protective element can be formed in a common sheet metal formed part. The stop disk can preferably be formed on the end face of the inner bearing sleeve facing away from the vehicle body. In this case, the stop disk can be extended outwards in the radial direction with a supporting section that merges into a stop wall angled therefrom, which forms the protective element. It is preferred if the protective element is arranged at the same height as the subframe bearing, viewed in the vehicle's vertical direction, in order to achieve a favorable load path. In this case, the protective element can be arranged approximately in line behind the subframe bearing, viewed in the vehicle's longitudinal direction.

[0019] The invention and its advantageous developments and further developments as well as their advantages are explained in more detail below with reference to drawings.

[0020] They show: Fig. 1 in a roughly schematic view from above a rear section of an electrically powered two-track motor vehicle; Fig. 2 the subframe in its own right in combination with the traction battery; Fig. 3 a sectional view of a subframe bearing; and Fig. 4 another, compared to the Fig. 3 simplified sectional view of the subframe bearing.

[0021] In the Fig. 1 shows a top view of the rear section of a two-track, electrically powered motor vehicle. Fig. The vehicle rear axle shown in Figure 1 has a rear subframe 1, which is constructed in an approximately closed frame-like manner, with subframe longitudinal members 3 spaced apart from one another in the vehicle transverse direction y, as well as with front and rear subframe cross members 5, 7. These extend in the vehicle transverse direction y and connect the two subframe longitudinal members 3 to one another at front and rear corner nodes. The two subframe longitudinal members 3 are extended forwards and backwards in the vehicle longitudinal direction x, each beyond the corner nodes, and each have bearing eyes 13 at their ends for subframe bearings 15, of which Fig. 1 and in the Fig. 2 only the rear right subframe bearing 15 is shown, via which the subframe 1 is attached to the vehicle body 17 ( Fig. 4) can be connected.

[0022] On the outside of the two subframe longitudinal members 3, control arm brackets are formed, to which wheel control arms of a wheel suspension for the rear wheels 19 of the motor vehicle are pivoted. The rear wheels 19 are driven by an electric motor 21 carried by the subframe 1. This motor can be supplied with electrical energy by a traction battery 25. The traction battery 25 is installed, for example, in the vehicle underbody and in the vehicle's longitudinal direction x directly in front of the subframe 1 of the motor vehicle.

[0023] Based on the Fig. 3 and Fig. 4, the structure of the subframe bearing 15 is described below: The subframe bearing 15 has a radially outer bearing sleeve 27 as the subframe-side bearing component and a radially inner bearing sleeve 29 as the body-side bearing component. An elastomer body 31 is vulcanized between the two bearing sleeves 27, 29. In the Fig. 3 shows the subframe bearing 15 disassembled from the bearing eye 13 of the subframe. In the assembled position ( Fig. 4) the outer bearing sleeve 27 is pressed into the bearing eye 13 of the subframe 1.

[0024] The subframe bearing 15 is connected via a screw connection point S ( Fig. 4) is attached to the vehicle body 17 by means of a screw bolt 33, which is guided through the inner bearing sleeve 29 and, by means of a screw nut 35, rigidly clamps the inner bearing sleeve 29 between its bolt head 37 and the screw nut 35. The screw nut 35 can be fixed to the vehicle body as a weld nut. Alternatively, a through-hole molded onto the vehicle body 17 with an internal thread can be used instead of the screw nut 35.

[0025] A radially expanded stop disc 39 is arranged between the end face of the inner bearing sleeve 29 facing away from the vehicle body 17 and the bolt head 37. This partially covers the height stops 41 of the outer bearing sleeve 27 ( Fig. 3) or the elastomer body 31 ( Fig. 4), whereby an axial movement of the outer bearing sleeve 27 relative to the inner bearing sleeve 29 rigidly connected to the vehicle body 17 is limited.

[0026] In the figures, the two bearing sleeves 27, 29 are rotationally symmetrical and arranged coaxially to each other on a common bearing axis. This axis is aligned in the vehicle vertical direction z and is aligned with the screw axis (i.e., the central longitudinal axis) of the screw bolt 33. The Fig. 3 and Fig. The subframe bearings 15 shown in Figure 4 are identical in terms of their basic structure and function, but the Fig. 4 shown subframe bearings 15 are shown in simplified form for a simpler understanding of the invention.

[0027] As from the Fig. 3 or Fig. 4, the stop disc 39 is extended outward in the radial direction by a support section 43, which at a transition edge merges into a stop wall 45 aligned parallel to the bearing eye 13. The stop wall 45 is arranged at the same height as the subframe bearing 15, viewed in the vehicle vertical direction z, and is positioned behind the subframe bearing eye 13 via a deformation clearance 44, viewed in the direction of travel FR.

[0028] In a rear-end crash situation described below, the stop wall 45 and the support section 43 act as a protective element 46 which, together with the screw connection point S, is arranged in a load path L ( Fig. 4) is involved. According to the Fig. 4, the protective element 46 and the stop disc 39 form a one-piece sheet metal part B.

[0029] The impact forces F introduced via the load path L are A from the stop wall 45, the support section 43, the stop disc 39 and the screw connection point S into the vehicle body 17.

[0030] In such a rear-end crash, the impact forces F A initially introduced into the stop wall 45 and from there forwarded into the vehicle body 17 via the supporting section 43 and the inner bearing sleeve 29, which is clamped to the vehicle body 17 by means of the screw bolt 33. In this way, a load path L ( Fig. 4) is provided, over which the impact forces F Acan be introduced into the vehicle body 17. As long as the protective element 46 is not yet plastically deformed, the load path L is decoupled from the elastomer body 31 and the outer bearing sleeve 27 in terms of force.

[0031] Only upon plastic deformation of the protective element 46, acting as a deformation element, and after the deformation clearance 44 has been exhausted, does its stop wall 45 come into force-transmitting contact with the subframe bearing eye 13, causing the elastomer body 31 to deform to a block dimension. The crash loading of the subframe bearing 15 therefore occurs at a significantly later point in the crash—compared to the prior art—and only after the protective element 46 has undergone its deformation. This reduces the risk of premature destruction of the rear subframe bearings 15 of the subframe 15.

Claims

[1] Body structure for a two-track vehicle, comprising a subframe (1) for a vehicle rear axle, wherein the subframe (1) is connected to the vehicle body (17) via a screw connection point (S), wherein the subframe (1) is connected to the vehicle body (17) via at least one subframe bearing (15), which subframe bearing (15) is constructed from a subframe-side bearing component (27) and a body-side bearing component (29), between which a vibration damping unit (31) is arranged, wherein the body-side bearing component (29) of the subframe bearing (15) is connected to the vehicle body (17) via the screw connection point (S), characterized bythat the body structure has at least one protective element (46) on the side of the screw connection point (S) facing the rear crash, which is connected to the vehicle body (17) via the screw connection point (S), and that the screw connection point (S) has a screw bolt (33) with which both the body-side bearing component (29) of the subframe bearing (15) and the protective element (46) are screwed to the vehicle body (17), and that in the event of a rear crash, the protective element (46) and the screw connection point (S) are integrated in a load path (L) via which the introduced impact forces (F A ) can be passed from the protective element (46) into the vehicle body (17). [2] Body structure according to claim 1, characterized by that the vibration damping unit (31) connected between the two bearing components (27, 29) is decoupled from the load path (L). [3] Body structure according to claim 1 or 2, characterized by that the vibration damping unit (31) is an elastomer body. [4] Body structure according to claim 3, characterized by that the body-side bearing component (29) is a radially inner bearing core, and that the subframe-side bearing component (27) is a radially outer bearing sleeve, and that the bearing core designed as a body-side bearing component (29) is a hollow-cylindrical inner bearing sleeve through which the screw bolt (33) can be guided, and that the inner bearing sleeve (29) together with the protective element (46) can be rigidly clamped to the vehicle body (17) with the screw bolt (33), and that the radially outer bearing sleeve (27) is elastically and flexibly connected to the radially inner bearing sleeve (29) via the elastomer body (31). [5] Body structure according to claim 4, characterized bythat the inner and outer bearing sleeves (27, 29) lie coaxially to one another on a common bearing axis of the subframe bearing (15), and that the bearing axis is aligned at right angles to the vehicle longitudinal direction (x). [6] Body structure according to claim 4 or 5, characterized by that the subframe bearing (15) has at least one stop disc (39) which cooperates with the outer bearing sleeve (27) and / or with the elastomer body (31) in order to limit an axial and / or radial movement between the radially inner and outer bearing sleeves (27, 29). [7] Body structure according to claim 6, characterized by that the stop disc (39) is connected to the protective element (46) in a force-transmitting manner, specifically to form a component (B) made of the same material and / or in one piece, or that the stop disc (39) is connected to a bolt head (37) of the screw bolt (33) made of the same material and / or in one piece. [8] Body structure according to claim 4, 5 or 6, characterized by that the protective element (46) is spaced rearwardly in the vehicle longitudinal direction (x) by a deformation clearance (44) from the subframe bearing (15), and that the outer bearing sleeve (27) of the subframe bearing (15) is pressed into a bearing eye (13) of the subframe (1), and that the deformation clearance (44) is defined between the subframe bearing eye (13) and the protective element (46). [9] Body structure according to claim 8, characterized by that the protective element (46) is designed as a plastically deformable deformation element, and that in the event of a rear-end crash, impact forces (F A ) into the subframe bearing eye (13) and into the outer bearing sleeve (27). [10] Body structure according to one of claims 8 or 9 and claim 6 or 7, characterized bythat the stop disk (39) is formed on the end face of the inner bearing sleeve (29) facing away from the vehicle body (17), and / or that the protective element (46) has a stop wall (45) which is spaced from the subframe bearing (15) by the deformation clearance (44) in the vehicle longitudinal direction (x) and is arranged at the same height as the subframe bearing (15) in the vehicle vertical direction (z), and that the stop disk (39) is extended outwards in the radial direction by a support section (43) which supports the stop wall (45).

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