Rear Axle Subframe Support Structure for EV Battery Crash Load Paths
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Solution Overview
Problem
The crash-sensitive plug connections at the traction battery's connection point in electrically operated vehicles are at risk of damage during a rear-end collision due to the rear drive unit shifting towards the battery-side connection point, causing potential damage from rear-crash forces.
Innovation Solution
The rear axle subframe is extended with support elements at its front corner nodes, which bridge the longitudinal offset between the subframe cross member and the battery cross member, integrating the rear axle subframe and battery cross member into a rear crash load path, allowing the subframe to absorb crash forces without damaging the battery connectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the rear axle subframe is positioned with a free longitudinal offset from the battery cross member, then the subframe can be easily mounted and supply lines can be routed, but the battery-side connection point becomes vulnerable to damage in rear-end crashes
Solution Approach 1:
The support elements are pre-positioned on the rear axle subframe at its front corner nodes, extending toward the battery cross member. This preliminary positioning ensures that in the event of a rear-end crash, the subframe is already configured to engage the battery cross member through the support elements, creating a load path that protects the battery connection point before the crash forces are applied.
Solution Approach 2:
The support elements act as intermediary components between the rear axle subframe and the battery cross member. These elements bridge the free longitudinal offset, enabling force transmission from the subframe to the battery cross member during a crash, thereby protecting the battery-side connection point while maintaining the mounting flexibility provided by the offset.
2Reliability
If the support elements bridge the longitudinal offset between subframe cross member and battery cross member, then crash forces are redirected away from battery connectors, but the structural complexity of the rear axle subframe increases
Solution Approach 1:
The rear axle subframe is segmented by adding discrete support elements at its front corner nodes. These support elements are individual components that extend from the subframe cross member toward the battery cross member, creating a modular structure that provides crash protection while maintaining manufacturing simplicity. The segmentation allows the support elements to be designed and manufactured separately and then integrated into the subframe.
Data Source
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AI summary
The invention relates to a vehicle body structure for an electrically operated vehicle, with a mounting chamber (8) for a traction battery (9), which mounting chamber (8) is open towards the bottom of the vehicle in the vehicle vertical direction (z), is delimited towards the top of the vehicle by a floor sheet metal part (10) which forms the vehicle floor, and is delimited towards the rear of the vehicle in the vehicle longitudinal direction (x) by way of a vehicle body-side battery crossmember (13), wherein a rear axle subframe (21) is attached via subframe bearings (23) to the vehicle body behind the battery crossmember (13) in the vehicle longitudinal direction (x), wherein the rear axle subframe (21) has lateral subframe longitudinal carriers (25) which are connected at front corner nodes (E) to a front subframe crossmember (27), wherein the front subframe crossmember (27) is spaced apart from the battery crossmember (13) by way of a longitudinal offset (Δx). According to the invention, the subframe (21) is extended at each of the two front corner nodes (E) by way of a supporting element (47) which at least partially bridges the free longitudinal offset (Δx) between the subframe crossmember (27) and the battery crossmember (13). In the case of a rear crash, the subframe (21) is incorporated by way of its two supporting elements (47) and its two subframe longitudinal carriers (25) and the battery crossmember (13) into a rear crash load path (Lx).