Vehicle Seat Anti-Submarining Airbag With Tensioned Web Support

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Solution Overview

Problem

The phenomenon of submarining during collisions in vehicle seats, where the pelvic bone displaces vertically downwards, compromising the effectiveness of the seat belt, is not adequately addressed by existing comfort features, leading to a trade-off between safety and comfort.

Innovation Solution

An anti-submarining system integrated into the vehicle seat, comprising an inflatable airbag and a web tensioned between structural seat components, which cooperatively form a reaction surface to support the airbag and limit pelvic displacement during collisions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If cushioning and spring structure are provided in the vehicle seat, then comfort is improved, but the risk of submarining increases during collision

Engineering Contradiction:
ImprovecomfortVSAvoidsafety
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The seat structure is segmented into multiple functional layers: the upper comfort layer with cushioning and spring structure, and the lower anti-submarining layer with rigid support elements. This segmentation allows each layer to perform its specific function independently - the upper layer provides comfort while the lower layer prevents submarining during collision

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A rigid support structure is introduced as an intermediary element between the comfort layer and the seat pan. This intermediary structure transmits collision forces directly to the seat frame, preventing the cushioning from allowing excessive pelvic displacement while maintaining comfort during normal use

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If the seat back is inclined backwards for relaxation, then comfort is improved, but the risk of submarining increases due to unfavorable rotation of torso and pelvic bone

Engineering Contradiction:
ImprovecomfortVSAvoidsafety
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The anti-submarining system is pre-configured with rigid support elements positioned to counteract the unfavorable rotation caused by seat back inclination. When collision occurs, these pre-positioned elements immediately provide the necessary counter-force to prevent pelvic bone rotation, effectively neutralizing the safety risk introduced by the relaxed seating position

Inventive Principle:
Principle #9Preliminary anti-action

3Reliability

If cushioning is removed to reduce submarining risk, then safety is improved, but comfort is reduced

Engineering Contradiction:
ImprovesafetyVSAvoidcomfort
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The seat is divided into functional zones where cushioning is retained in the upper portion for comfort while rigid support elements are positioned in the lower portion for safety. This spatial segmentation allows both comfort and safety requirements to be satisfied simultaneously without compromising either function

Inventive Principle:
Principle #1Segmentation

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 system effectively reduces the risk of submarining by providing a stiffening reaction surface that supports the airbag and maintains a favorable body position, enhancing safety without compromising comfort.

Implementation Method 1

The inflatable airbag is connected to an inflator which is configured to inflate the airbag in response to an airbag activation signal

Methodology Applied
Scientific EffectGas inflation: Pressure Increase

Implementation Method 2

the web tensioner is configured to set the at least one web from a slacked condition to a tensioned condition in response to a tensioner activation signal, whereby the thus tensioned web forms a reaction surface configured to support the inflated airbag from below in a direction upwardly towards a seated passenger

Methodology Applied
Scientific EffectMechanical tensioning: Tension

Data Source

PatentEP4620731A1An Anti-submarining system to be used in a vehicle seat and the use of such system
Publication Date: 2025.09.24 AUTOLIV DEV AB
  • EP4620731A1 patent drawingFigure 1A~2D
  • EP4620731A1 patent drawingFigure 3
  • EP4620731A1 patent drawingFigure 4A~5

AI summary

An anti-submarining system (10) to be used in a vehicle seat (20) is provided comprising an inflatable airbag (13), at least one web (11), and a web tensioner (12) coupled to the at least one web (11). The at least one web is configured to be arranged to extend between two opposing structural seat components (21), the at least one web is further configured to be arranged inside the seat (20) in a position between a spring structure (23) and an exterior upholstery (24) of the vehicle seat. The airbag is provided separate from and above the web (11) such that the airbag and the web vertically overlap, and is configured to be arranged in a position between the web and the exterior upholstery. The airbag is connected to an inflator which is configured to inflate the airbag in response to an airbag activation signal.