Slotted Crash Box Partitions for Weld-Safe Energy Absorption
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Solution Overview
Problem
The crash management systems in electrically driven motor vehicles face challenges in absorbing and transmitting energy during crashes due to the absence of a large constructional block in front of the passenger cell, requiring higher energy absorption and transmission capabilities, which puts strain on welded joints and demands lightweight aluminum construction.
Innovation Solution
The crash box design features at least two hollow chambers separated by partitions with slots at the vehicle-side and bumper-side ends, allowing inward bending as a hinge to reduce tensile stresses and optimize energy absorption and transmission, while maintaining weld seam integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large constructional block (internal combustion engine and transmission) is arranged in front of the passenger cell, then energy is conducted away from the passenger cell during a crash, but in electrically driven motor vehicles this space is empty and cannot contribute to energy absorption
Solution Approach 1:
The partition geometry is changed by introducing slots at specific positions and orientations, transforming the rigid partition into a structure that enables controlled deformation. This allows the crash box to adapt its energy absorption characteristics to compensate for the missing engine block, maintaining passenger cell protection in electric vehicles.
2Reliability
If the crash management system is designed to absorb higher energy levels in electric vehicles, then energy absorption capability is improved, but the demands on welded joints become very exacting and may fail
Solution Approach 1:
The slots in the partition are designed to trigger inward bending of the crash box at specific locations during a crash. This preliminary deformation path guides the energy absorption process, ensuring that the maximum tensile stresses do not concentrate at the welded joints connecting the crash box to the longitudinal members, thereby preserving joint integrity while maintaining high energy absorption capability.
3Weight of moving object
If lightweight aluminum crash management systems are used to reduce vehicle weight and emissions, then weight is reduced, but the material may be more susceptible to joint failure under high stress
Solution Approach 1:
The partition geometry is modified with slots that create controlled deformation zones. This changes the stress distribution parameters during crash deformation, reducing peak tensile stresses at the welded joints. This allows lightweight aluminum materials to maintain sufficient joint reliability under crash conditions while achieving weight reduction goals.
4Strength
If the partition is made rigid without slots to maintain structural integrity, then joint strength is preserved, but the folding and energy absorption of the crash box is reduced
Solution Approach 1:
The partition is segmented by introducing slots that create controlled weak points. These slots allow the partition to bend inward at specific locations during a crash, enabling the crash box to fold and absorb energy while the overall partition structure remains intact and maintains its connection to the outer and inner walls.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design enhances energy absorption and transmission capabilities, maintaining weld seam integrity during high penetration, thereby improving passenger safety and reducing the risk of joint failure.
Implementation Method 1
The inward bending of the crash box functions here substantially as a hinge and contributes to reducing the tensile stresses at the outer weld seams
Implementation Method 2
have the task, in the event of a crash, of absorbing the energy introduced via the bumper arrangement or a bumper beam in the crash boxes by corresponding folding or deformation of the crash boxes
Implementation Method 3
transmitting excess energy into the frame or the longitudinal members of the motor vehicle in order thereby to conduct the energy introduced into the motor vehicle by the crash around the passenger cell
Data Source
AI summary
The invention relates to a crash box (1) for a bumper arrangement (2) of a motor vehicle, having at least two closed hollow chambers (5, 6, 7) which are formed over their entire longitudinal extent from a bumper-side end (3) as far as a vehicle-side end (4) and which are in each case separated from one another by a partition (10, 11) running between an outer wall (8) and an inner wall (9) of the crash box (1). The invention is distinguished in that the partition (10, 11) is provided with a slot (13) at its vehicle-side end (4) in its half (12) directed toward the inner wall (9) of the crash box (1).