Multi-Density Bumper Foam Structure for Pedestrian and Low-Speed Impact
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Solution Overview
Problem
Existing energy absorption devices for vehicle bumpers struggle to balance pedestrian protection and low-speed crash requirements while optimizing installation space and vehicle appearance.
Innovation Solution
An energy absorption device comprising a first deformation element with a significantly lower density than a second deformation element, providing localized stiffening, which is inserted into the first element, ensuring both pedestrian protection and low-speed crash performance without compromising vehicle design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foam materials of similar density are used for first and second deformation elements, then manufacturing is simpler, but energy absorption performance for both pedestrian protection and low-speed crash cannot be optimized simultaneously
Solution Approach 1:
The patent applies local quality by using foam materials with different densities in different regions: the first deformation element uses lower density foam (20-50 g/l) for pedestrian protection, while the second deformation element uses higher density foam (at least 50 g/l higher) for low-speed crash performance. This regional differentiation allows each element to be optimized for its specific function, resolving the contradiction between performance optimization and manufacturing simplicity.
Solution Approach 2:
The patent employs composite materials by combining two different foam materials with significantly different densities in a single energy absorption device. The first deformation element uses one foam type while the second uses another, creating a composite structure that delivers both pedestrian protection and low-speed crash performance, thereby resolving the performance contradiction despite increased manufacturing complexity.
2Strength
If the bumper structure is made stiffer to reduce intrusion in low-speed crashes, then vehicle damage is minimized, but pedestrian protection is compromised due to increased rigidity
Solution Approach 1:
The patent resolves this contradiction by applying local quality through spatial differentiation of stiffness: the first deformation element with lower density foam provides softer deformation for pedestrian protection, while the second deformation element with higher density foam provides stiffer resistance for low-speed crash protection. This localized variation in mechanical properties allows the bumper to exhibit context-dependent behavior.
Solution Approach 2:
The patent segments the bumper structure into two distinct deformation elements with different mechanical properties. The first element handles pedestrian impacts with softer foam, while the second element handles low-speed crashes with stiffer foam. This segmentation allows each segment to be optimized for its specific protective function without compromising the other.
3Loss of energy
If larger deformation elements are used to improve energy absorption, then collision energy is better absorbed, but installation space requirements increase and vehicle aesthetics are compromised
Solution Approach 1:
The patent applies local quality by concentrating the high-density second deformation element only in the regions where front longitudinal members extend, rather than using high-density foam throughout the entire bumper. This localized approach provides targeted energy absorption where most needed while minimizing overall volume and preserving vehicle aesthetics.
Solution Approach 2:
The patent uses parameter changes by varying the density parameter of the foam material between two distinct elements. The first element uses lower density (20-50 g/l) for pedestrian protection with larger volume, while the second element uses higher density (at least 50 g/l higher) for compact energy absorption in critical regions, optimizing both energy absorption efficiency and space utilization.
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 device effectively absorbs collision energy, minimizing vehicle damage and intrusion, while maintaining pedestrian safety and improving insurance ratings, with reduced installation space and enhanced vehicle aesthetics.
Implementation Method 1
a first deformation element (8) at the front of the bumper (4) The first deformation element (8) is a molded foam part extending over the width of the bumper (4)
Implementation Method 2
at least one second deformation element (10) inserted into the first deformation element (8), with a density at least 50 g/l higher than that of the first deformation element The second deformation element forms a local stiffening of the first deformation element
Implementation Method 3
The core idea of the invention is to provide an energy absorption device made of a composite foam component whose components have significantly different densities and thus significantly different stiffnesses
Data Source
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AI summary
The invention relates to an energy absorption device for a bumper (4) of a motor vehicle. The energy absorption device has a first deformation element (8) on the front side of the bumper (4). The first deformation element (8) is a foam shaped part which extends over the width of the bumper (4) and has a density of from 20 to 50 g/l. At least one second deformation element (10), with a density which is at least 50 g/l higher than the first deformation element (8), is inserted into the first deformation element (8).