Vehicle Occupant Protection Device with Head Movement Detection
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Solution Overview
Problem
Conventional occupant protection devices fail to accurately determine protection by airbags and appropriately switch seat belt force limiter loads due to reliance on vehicle left-right acceleration alone, neglecting variations in vehicle front-rear acceleration and occupant position during frontal collisions.
Innovation Solution
A vehicle occupant protection device incorporating a seat belt with a selectable force limiter, an airbag, a movement direction detector, an initial position detector, and a control unit that determines whether the occupant's head region will move outside the airbag's protection area based on detected movement direction and position, maintaining a high force limiter load if necessary to ensure proper protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the belt load is switched to a low load based only on occupant's physique and left-right acceleration, then the load from the seat belt is reduced, but the determination accuracy of airbag protection is insufficient
Solution Approach 1:
The patent transitions from using only left-right acceleration (one dimension) to incorporating both front-rear and left-right accelerations (three dimensions) to determine airbag protection. This dimensional expansion enables accurate calculation of the occupant's movement trajectory and determination of whether the head region will move outside the airbag protection area, thereby resolving the insufficiency in determination accuracy while maintaining the seat belt load reduction benefit
2Reliability
If the belt load is maintained at a high load to ensure protection when occupant moves outside airbag range, then protection reliability is improved, but the seat belt load cannot be appropriately reduced
Solution Approach 1:
The patent implements a feedback mechanism where the control unit continuously monitors front-rear and left-right accelerations, calculates the occupant's movement trajectory, and determines in real-time whether the head region will move outside the airbag protection area. Based on this feedback, the force limiter load is dynamically adjusted - reduced to low load when protection is confirmed, and maintained at high load when protection cannot be ensured - thereby achieving both protection reliability and appropriate load switching
Data Source
AI summary
A vehicle occupant protection device includes: a seat belt device having a selectable force limiter that is configured to switch a force limiter load from a high load to a low load; an airbag device that deploys an airbag in front of the occupant; a movement direction detector that detects a direction in which a head region of the occupant will move relative to the vehicle at the time of frontal collision; an initial position detector that detects a position of the head region prior to the movement; and a control unit that makes a determination whether or not the head region will move outside of an area of protection by the airbag based on detection results of the movement direction detector and the initial position detector and, in a case in which the determination is affirmative, maintains the high load of the force limiter load.