Open-Profile Crash Box Assembly for Lightweight Bumper Deformation

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Solution Overview

Problem

Existing bumper assemblies in motor vehicles have high dead weight due to their closed profile shape and multi-part design, which can lead to corrosion and complex manufacturing, and do not effectively manage deformation for impact energy absorption and pedestrian protection.

Innovation Solution

A one-piece, open hollow profile crash box design with integrated molded tabs for easy attachment to the bumper cross member and vehicle structure, ensuring minimal weight, reduced corrosion risk, and controlled deformation direction for optimal energy absorption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If closed hollow profile sections are used for crash boxes, then structural strength is improved, but dead weight increases and corrosion risk increases

Engineering Contradiction:

Improvestructural strengthVSAvoiddead weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The crash box is divided into a multi-part construction consisting of a hollow profile section and separately attachable reinforcement elements (such as tabs or brackets). This segmentation allows the use of lighter gauge material for the main profile while adding strength only where needed through strategic reinforcement elements, reducing overall weight compared to a fully thick-walled closed section.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Reinforcement is applied locally at critical stress points (front end, rear end, mounting locations) rather than uniformly throughout the entire crash box structure. This allows the majority of the profile to use lighter material while maintaining structural integrity where loads are applied, optimizing the strength-to-weight ratio.

Inventive Principle:

Principle #3Local quality

2Strength

If closed hollow profile sections are used for crash boxes, then structural strength is improved, but manufacturing complexity increases due to multi-part design and welding requirements

Engineering Contradiction:

Improvestructural strengthVSAvoidmanufacturing complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The crash box is divided into a multi-part construction consisting of a hollow profile section and separately attachable reinforcement elements (such as tabs or brackets). This segmentation allows the use of lighter gauge material for the main profile while adding strength only where needed through strategic reinforcement, reducing overall weight compared to a fully thick-walled closed section.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The reinforcement elements are designed to be integrally formed with or pre-attached to the hollow profile section, combining multiple functional components into a single assembly unit. This merging reduces the number of separate parts and simplifies installation while maintaining the structural benefits of reinforcement.

Inventive Principle:

Principle #5Merging (Combining)

3Strength

If closed hollow profile sections are used for crash boxes, then structural strength is improved, but corrosion resistance worsens due to moisture and dirt penetration

Engineering Contradiction:

Improvestructural strengthVSAvoidcorrosion resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The closed hollow profile is opened at selected locations to create drainage holes or gaps that allow moisture and dirt to escape. This extraction of the fully enclosed structure prevents water trapping and corrosion while maintaining the structural integrity of the profile through strategic placement of openings away from critical load-bearing areas.

Inventive Principle:

Principle #2Taking out (Extraction)

4Reliability

If anti-corrosive coating is applied to crash boxes, then corrosion protection is improved, but manufacturing complexity increases due to drainage hole requirements

Engineering Contradiction:

Improvecorrosion protectionVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #2Taking out (Extraction)

5Strength

If multi-part crash boxes are used, then structural strength is improved, but manufacturing cost increases due to welding of multiple parts

Engineering Contradiction:

Improvestructural strengthVSAvoidmanufacturing cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The crash box is divided into a multi-part construction consisting of a hollow profile section and separately attachable reinforcement elements (such as tabs or brackets). This segmentation allows the use of lighter gauge material for the main profile while adding strength only where needed through strategic reinforcement, reducing overall weight compared to a fully thick-walled closed section.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Inventive Principle:

Principle #5Merging (Combining)

6Strength

If crash boxes are designed for optimal energy absorption, then impact protection is improved, but pedestrian protection may worsen due to uncontrolled deformation

Engineering Contradiction:

Improveimpact protectionVSAvoidpedestrian injury risk

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The crash box is designed with controlled deformation characteristics that allow progressive collapse under impact loads. The structure is engineered to deform in a predictable manner, transitioning from a rigid energy-absorbing structure to a more compliant form that reduces peak forces on pedestrians while maintaining protection during the impact event.

Inventive Principle:

Principle #15Dynamics

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 solution results in a lightweight, cost-effective bumper assembly that minimizes vehicle damage and enhances pedestrian protection by controlling deformation direction, preventing rotation and buckling, and reducing corrosion risk.

Implementation Method 1

the tab formed on the channel base, which extends at least to the alignment line of the legs or even beyond, is pressed against the end faces of the legs, so that the legs and with them the entire profile section are pressed towards the vehicle in the longitudinal direction of the vehicle and deformed

Methodology Applied

Scientific EffectDeformation: Deformation

Implementation Method 2

The crash box is essentially compressed in the longitudinal direction of the vehicle (x-axis)

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 3

If the crash box is coated with an anti-corrosive paint, for example, excess paint can easily drain from the cavity, which is open on one side, without the need for drainage openings or holes in any of the walls

Methodology Applied

Scientific EffectGravity: Gravitation

Data Source

PatentEP4339036B1Motor vehicle with bumper arrangement

Publication Date: 2025.10.22 GEDIA GEBR DINGERKUS

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AI summary

Motor vehicle with at least one bumper assembly, wherein a first bumper assembly (1) comprises a first bumper cross member (2) and at least two spaced-apart first crash boxes (3), each of which is attached at a first end (4) to one of the two end-near regions of the bumper cross member (2) and each of which is attached at a second end (5) to parts of the vehicle structure, wherein each crash box (3) comprises a channel-like profile section with a channel base (6) and two legs (7, 8) projecting transversely therefrom, wherein each profile section has at least at its frontal first end (4) a molded tab (9) projecting transversely, folded over from the channel base, with which the crash box (3) is attached to the bumper cross member (2).