Airbag Control Device with Tear Seam Ventilation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing airbag module control devices face issues with parts flying inside the gas space and unwanted gas introduction due to pyrotechnic charges, and the need for direct adjacency of components limits structural flexibility.

Innovation Solution

An airbag module with a control device featuring a second casing that encloses a separate gas space, where the control element is sewn to the second casing when unfilled and decouples when filled, using a tear seam that withstands high forces and divides the gas space into regions to generate a large opening force, allowing for active control of ventilation and airbag depth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a pyrotechnic actuator is used to control the throttle element, then the ventilation can be actively controlled, but parts fly inside the gas space and hot gases are created

Engineering Contradiction:

Improveactive control of ventilationVSAvoidparts flying and hot gases inside airbag

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The invention divides the system into two separate gas spaces: a first gas space for the airbag and a second gas space for the actuation gas. This segmentation isolates the pyrotechnic actuation process from the airbag interior, preventing parts and hot gases from contaminating the airbag while maintaining active control capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A second casing acts as an intermediary container that holds the pyrotechnic charge and actuation gas separately. The control element transmits force through this intermediary structure to actuate the throttle element, thereby mediating between the pyrotechnic actuation mechanism and the ventilation control function while preventing direct contamination.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the second casing is directly adjacent to the vent opening for direct control, then control effectiveness is improved, but structural flexibility is reduced

Engineering Contradiction:

Improvecontrol effectivenessVSAvoidstructural flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The control element is implemented as a flexible strap that can be sewn to both the second casing and the throttle element. This flexible connection allows the second casing to be positioned at various locations within the airbag structure while still maintaining effective mechanical coupling for actuation, thereby preserving both control effectiveness and structural flexibility.

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If the tear seam is made strong to withstand high forces, then connection reliability is improved, but it becomes difficult to decouple when needed

Engineering Contradiction:

Improveconnection reliabilityVSAvoiddecoupling when filled

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The tear seam is designed with asymmetric strength characteristics: it maintains high strength in the unfill ed state to ensure reliable connection, but is engineered to fail at a predetermined location when subjected to the pressure forces generated during gas space filling. This dynamic behavior allows the seam to transition from a strong connection to a controlled release based on operational conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The tear seam's mechanical properties are designed to change based on the pressure parameter in the second gas space. When the gas space is unfilled, the seam withstands high forces; when filled, the pressure causes the seam to tear at a weak point, enabling automatic decoupling. This parameter-dependent behavior resolves the contradiction between strength and ease of release.

Inventive Principle:

Principle #35Parameter changes

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 design prevents parts from flying inside and unwanted gas introduction, while enabling active control of ventilation and airbag depth with improved structural flexibility and reproducibility.

Implementation Method 1

a gas source which serves to fill the second gas space with gas

Methodology Applied

Scientific EffectGas expansion: Pressure Increase

Implementation Method 2

the tear seam divides the unfilled gas space into two regions divided by the tear seam

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Data Source

PatentUS9827941B2Airbag module with a control device

Publication Date: 2017.11.28 AUTOLIV DEV AB

AI summary

An airbag module including a first casing enclosing a first gas space, a first inflator and a control device for controlling ventilation of the first gas space or the shape of the first casing. The control device includes a second casing (42) enclosing a second gas space and a gas source. The second gas space is bordered by a permanent edge connection, and further includes a control element such as a strap (60), whose first end is connected to the first casing and whose second end is sewn to the second casing (42) by a tear seam (49), and is decoupled from the second casing (42) upon filling of the second gas space. The tear seam (49) touches or intersects the edge connection at two points so that the tear seam divides the second gas space into two regions (43a, 43b).