Webbing Take-Up Device Compact Force Limiter Switching
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Solution Overview
Problem
Existing seatbelt retractors require a longer movement stroke for the EA operation control member to switch between engaged and disengaged positions, leading to bulkier gas generators due to the need for longer movement strokes, which complicates the design and increases size and weight.
Innovation Solution
A webbing take-up device with a switching member that can be moved between two positions using an operation member, allowing for a compact configuration by reducing the movement stroke required for switching between high-load and low-load force limiter settings, and utilizing a biasing force or placing member to position the switching member when the operation member is not in operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the EA operation control member is moved between engaged and disengaged positions using a gas generator, then the force limiter load can be switched between high-load and low-load, but the movement stroke becomes longer resulting in a bulkier gas generator
Solution Approach 1:
The switching mechanism is divided into two independent components: the switching member that moves between positions, and the operation member that actuates the switching member. This segmentation allows the gas generator to only move the operation member (short stroke) rather than the entire EA operation control member (long stroke), reducing the gas generator size while maintaining force limiter load switching capability
Solution Approach 2:
The operation member serves as an intermediary between the gas generator and the switching member. The gas generator actuates the operation member, which in turn actuates the switching member to change its disposed position. This intermediary mechanism allows for reduced movement stroke of the gas generator while achieving the same functional outcome of switching between high-load and low-load force limiter settings
Data Source
AI summary
A webbing take-up device including: a spool on which a webbing fitted over an occupant is taken up; a restricting member restricting a rotation of the spool in the pullout direction under specific circumstances; a force limiter mechanism permitting the rotation of the spool in the pullout direction when a force limiter load or a higher load is imparted while the restricting member is restricting the rotation of the spool in the pullout direction; a switching member being capable of switching between a disposed position at a first position and a disposed position at second position, and provided between the first position and the second position; and an operation member being capable of being switched between operation and non-operation, whereby the disposed position of the switching member is switched between the first position and the second position and the force limiter load is switched between a high-load and a low-load.