Multi-Chamber Crash Box Structure for Predictable Bumper Folding
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Solution Overview
Problem
Existing bumper assemblies face issues with joint damage and failure during crashes, leading to uncontrolled energy transfer and increased risk of passenger compartment injury due to high stress on joining connections between crash boxes and cross members.
Innovation Solution
A crash box design featuring at least one outer and one inner hollow chamber, separated and spaced apart in the front section, with independent energy dissipation paths, and a material-bonded connection to the cross member, ensuring predictable folding and energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the crash box is bolted to the cross member with screw connections, then the crash box can be securely joined to the cross member, but the screw connections are subjected to extremely high loads in the event of a crash which can lead to damage or destruction of the joints
Solution Approach 1:
The crash box is divided into multiple chambers (first hollow chamber and second hollow chamber) that are separated in the front region but connected in the end region. This segmentation allows each chamber to independently absorb and distribute crash forces, preventing concentrated loads from overwhelming the joint connections to the cross member.
Solution Approach 2:
The invention transitions from a single-chamber design to a multi-chamber design with chambers arranged in both longitudinal and transverse dimensions. The chambers are separated by a partition wall in the front region, creating a three-dimensional energy absorption structure that distributes forces across multiple planes and reduces peak loads on joints.
2Ease of operation
If the contact area between the crash box and cross member is reduced in the joining area, then the crash box can fold more effectively, but the joining areas experience extremely high loads which can lead to damage and destruction of the joints
Solution Approach 1:
The crash box is segmented into multiple chambers that can deform independently during folding. The partition wall between chambers allows controlled deformation patterns while maintaining structural integrity at the joint regions, enabling effective folding without compromising joint strength.
Solution Approach 2:
Different regions of the crash box have different structural characteristics: the front region has separated chambers optimized for folding and energy absorption, while the end region has connected chambers providing structural strength for reliable joint connections to the cross member.
3Strength
If the crash box consists of a single-chamber profile with walls bent away and joined to the cross member, then the joining areas can distribute loads over a larger area, but the folding behavior becomes significantly less favorable and less predictable
Solution Approach 1:
The single-chamber design is segmented into multiple chambers separated by partition walls. This segmentation creates predictable folding paths and deformation patterns while maintaining load distribution capabilities through the multi-chamber structure's geometric configuration.
Solution Approach 2:
The multi-chamber structure can be viewed as nested compartments within the overall crash box geometry. The partition walls create internal compartments that guide folding behavior predictably while the external geometry maintains effective load distribution to the cross member joints.
Data Source
Figure 1~3
Figure 4
Figure 5a~7b
AI summary
The invention relates to a crash box (1) for a bumper assembly (2) of a motor vehicle and is characterized in that the crash box (1) has at least one outer hollow chamber (5, 6) and at least one inner hollow chamber (7, 8) and a vehicle-side end section (9) and a bumper-side front section (10), wherein in the vehicle-side end section (9) the at least one outer hollow chamber (5, 6) is connected to the at least one inner hollow chamber (7, 8) and forms a closed multi-chamber profile, while in the bumper-side front section (10) the at least one outer hollow chamber (5, 6) is separated and spaced apart from the at least one inner hollow chamber (7, 8).