Vehicle Bumper Frame Longitudinal Sliding Interface

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Solution Overview

Problem

The rigidity of the bumper frame in vehicles can generate hard points during a front impact against a pedestrian, increasing the risk of injury, particularly at the femur or head.

Innovation Solution

The bumper frame is designed to move longitudinally inward during an impact by using a holding interface with transverse blocking means, such as ribs and projections, which allows it to absorb forces instead of transmitting them to the pedestrian, while maintaining the bumper skin's rigidity for aesthetic purposes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the bumper frame is made rigid to maintain bumper skin shape and provide structural support, then the perceived quality and structural integrity are improved, but the risk of injury to pedestrians in the event of a collision increases due to hard points generating significant forces

Engineering Contradiction:
Improvestructural integrityVSAvoidinjury risk
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The bumper frame is designed with a degree of freedom allowing longitudinal movement relative to the bumper crossmember through a sliding interface. This dynamic capability enables the frame to move inward during impact, converting the rigid structure into a controlled motion system that reduces peak forces on pedestrians while maintaining structural integrity during normal use

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The retaining interface transitions from a fixed rigid connection to a controlled sliding connection with specific friction characteristics. The interface allows movement under impact forces while preventing movement during normal operation, changing the mechanical parameter of connectivity from static to conditionally dynamic

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If the bumper frame is made movable to reduce impact forces on pedestrians, then the safety is improved, but the perceived rigidity and structural support for the bumper skin deteriorates

Engineering Contradiction:
Improveinjury riskVSAvoidperceived rigidity
Core Design Contradiction:
Object-affected harmful factorsVSStrength

Solution Approach 1:

The retaining interface is designed with friction characteristics that prevent longitudinal movement during normal operation, maintaining perceived rigidity. The same interface allows controlled movement when impact forces exceed the friction threshold, enabling safety functionality. This parameter-based control distinguishes between normal use and impact conditions

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If a rigid retaining interface is used to securely hold the bumper frame, then the structural stability is improved, but the ability to absorb impact forces and reduce pedestrian injury risk deteriorates

Engineering Contradiction:
Improvestructural stabilityVSAvoidimpact force transmission
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The retaining interface combines stability during normal operation with controlled mobility during impact. The sliding mechanism with friction characteristics provides structural stability when stationary but enables force absorption through controlled movement when impact forces are applied, resolving the contradiction between stability and impact absorption

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3978319B1Vehicle with supported bumper frame for reducing the risk of injuries
Publication Date: 2023.03.29 STELLANTIS AUTO SAS
  • EP3978319B1 patent drawingFigure 1~2
  • EP3978319B1 patent drawingFigure 3~4
  • EP3978319B1 patent drawingFigure 5

AI summary

[Vehicle (1) having at the front a bumper crossmember (2) extending in a transverse direction (Y) to the vehicle (1), a bumper skin (3), a bumper frame (4) disposed on the side of the bumper skin (3) oriented towards the interior of the vehicle, characterized in that the frame (4) has a retaining interface (41) cooperating with a support (6) fixed to the crossmember (2), the frame (4) resting vertically on the support (6) by its retaining interface (41), so as to prevent said frame (4) from moving along the vertical direction (Z) of the vehicle and downwards of the vehicle (1), while allowing free movement of the retaining interface (41) in a longitudinal direction (X) to the vehicle (1).