Under-Hood Airbag Layout With Tethered Pyrotechnic Deployment

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Solution Overview

Problem

Existing vehicle designs face challenges in packaging airbag systems under the hood while ensuring effective deployment and control of pedestrian kinematics during impacts, leading to constraints in vehicle design and potential damage to rigid vehicle components.

Innovation Solution

The airbag is positioned below the rearward end of the vehicle hood, with the pyrotechnic actuator located forward of the hood, and a tether extending from the actuator to the airbag, allowing separate packaging and deployment under the hood to control pedestrian kinematics relative to rigid vehicle components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the airbag is packaged under the vehicle hood, then the pedestrian protection function is achieved, but the packaging space is limited and deployment control becomes difficult

Engineering Contradiction:

Improvepedestrian protection functionVSAvoidpackaging space

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The system divides the airbag assembly into separate functional components: the airbag is packaged at the rearward end of the hood while the pyrotechnic actuator is positioned forward of the hood. This segmentation allows each component to be optimally positioned for its specific function, resolving the packaging space limitation while maintaining pedestrian protection capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A tether extends from the pyrotechnic actuator to the airbag, serving as an intermediary mechanism that transmits the deployment force across the hood. This intermediary allows the actuator to be positioned forward of the hood while still effectively deploying the airbag packaged at the rearward end, solving both the packaging space and deployment control issues.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the airbag is positioned to effectively control pedestrian kinematics, then pedestrian safety is improved, but packaging constraints and potential damage to rigid components increase

Engineering Contradiction:

Improvepedestrian safetyVSAvoiddamage to rigid vehicle components

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The airbag is pre-positioned and packaged under the hood in a compact state, ready for deployment before impact occurs. This preliminary positioning ensures that when deployed, the airbag is already in the optimal location to control pedestrian kinematics while minimizing the risk of damage to rigid vehicle components during the deployment process.

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

This configuration reduces packaging constraints and effectively deploys the airbag to absorb energy, controlling pedestrian kinematics and minimizing damage to vehicle components during impacts.

Implementation Method 1

a pyrotechnic actuator 20 disposed below the vehicle-forward end 16 of the hood 12

Methodology Applied

Scientific EffectPyrotechnic explosion: Detonation

Data Source

PatentUS12447924B2Airbag inflatable under vehicle hood

Publication Date: 2025.10.21 FORD GLOBAL TECH LLC

AI summary

A vehicle includes a hood having a vehicle-rearward end and a vehicle-forward end. An airbag is disposed below the vehicle-rearward end of the hood and is inflatable to the vehicle-forward end below the hood. A pyrotechnic actuator is disposed below the vehicle-forward end of the hood. A tether extends from the pyrotechnic actuator to the airbag.