Breakaway Bumper Frame Structure for Pedestrian Head Impact

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Solution Overview

Problem

Existing motor vehicle bumper frames pose a safety risk during pedestrian collisions due to their rigidity, which can increase the likelihood and severity of injuries, particularly to the head, and there is a need to improve safety and reduce hard points.

Innovation Solution

A bumper frame design with a rear wall comprising a connecting zone that includes breakable means to detach from the support during a pedestrian impact, allowing the frame to deform and reduce rigid contact with the pedestrian.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the bumper frame is made rigid to maintain the shape of the bumper skin, then the structural stability and support function are improved, but the safety during pedestrian impact deteriorates due to increased risk of head injuries

Engineering Contradiction:
Improvestructural stabilityVSAvoidpedestrian safety
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The bumper frame is divided into multiple zones with different rigidity characteristics: a rigid zone for maintaining bumper skin shape and a flexible zone with breakable means for pedestrian safety. This segmentation allows different parts of the same structure to serve different functions - the rigid portion provides structural support while the flexible portion reduces injury risk during impact.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the bumper frame are assigned different mechanical properties. The main body maintains high rigidity for structural stability, while specific localized areas (connecting zones) are designed with breakable means to provide flexibility and reduce hardness during pedestrian impact, thereby improving safety without compromising overall structural integrity.

Inventive Principle:
Principle #3Local quality

2Strength

If the bumper frame remains fixed to the support during impact, then the structural integrity is maintained, but the harmful effect of rigid contact with pedestrians increases

Engineering Contradiction:
Improvestructural integrityVSAvoidrigid contact
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The bumper frame transitions from a static fixed structure to a dynamic system that can change its state during impact. The breakable means are designed to remain intact during normal operation maintaining structural integrity, but to detach when subjected to pedestrian impact forces, thereby converting the structure from rigid to flexible at the moment of impact.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The breakable means are pre-configured in the frame structure during manufacturing, positioned at specific connecting zones. This preliminary arrangement ensures that when pedestrian impact occurs, the detachment action is automatically triggered without requiring additional control systems or active response mechanisms.

Inventive Principle:
Principle #10Preliminary action

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 frame design enhances pedestrian safety by minimizing rigid contact and promoting deformation, reducing the risk of injury and improving overall safety and perceived quality.

Implementation Method 1

the connecting zone comprising breakable means so as to detach the rear portion from the support in the event of a pedestrian impact

Methodology Applied
Scientific EffectFracture Mechanics: Fracture Mechanics

Implementation Method 2

the bumper skin deforms elastically upon contact with the obstacle, then returns to its position, without any permanent deformation remaining

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4400370B1Bumper skin reinforcement for a motor vehicle
Publication Date: 2025.06.25 STELLANTIS AUTO SAS
  • EP4400370B1 patent drawingFigure 1
  • EP4400370B1 patent drawingFigure 2
  • EP4400370B1 patent drawingFigure 3

AI summary

The invention relates to a frame (30) for a front bumper assembly (16) of a motor vehicle. The frame comprises a front panel (36) intended to be attached to an outer screen (20) of the bumper assembly, and a rear panel (38). The rear panel comprises a front portion (40) inclined relative to the front panel, and a rear portion (42) intended to rest on a support (26). The rear portion includes a connecting zone (48) intended to be connected to a support of the motor vehicle, the connecting zone comprising breakable means (50) for detaching the rear portion from the support in the event of a collision with the head (66) of a pedestrian.