Webbing Take-Up Spool Retreat Structure for Stable Limiter Load

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Solution Overview

Problem

Existing webbing take-up devices experience temporary increases in force limiter load due to abrasion of the winding portion by the distal end of the wire, which is not adequately addressed in existing technologies.

Innovation Solution

The webbing take-up device incorporates a spool with a retreat portion designed in a sloped or recessed shape at the winding portion, allowing the distal end of the wire to retreat, thereby reducing abrasion and suppressing temporary increases in force limiter load.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the wire is wound onto the winding portion of the spool, then the wire is properly stored and the spool structure is maintained, but the distal end portion of the wire causes abrasion of the winding portion leading to temporary increase in force limiter load

Engineering Contradiction:

Improveforce limiter load stabilityVSAvoidwire abrasion on winding portion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The winding portion is segmented into two functional zones: a main winding area and a retreat portion. This segmentation allows the wire to be stored in the main winding area while the distal end is directed to the retreat portion, separating the wire storage function from the wire end containment function to prevent abrasion.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The retreat portion acts as an intermediary structure between the wire distal end and the main winding portion. It provides a dedicated space that mediates the interaction, allowing the wire end to retreat into this intermediate zone rather than directly contacting and abrading the main winding portion.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the distal end portion of the wire is allowed to move freely, then the wire can be easily wound and unwound, but the wire presses against the winding portion causing abrasion and load increase

Engineering Contradiction:

Improvewire winding operationVSAvoidwire pressing and abrasion

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The retreat portion is designed with specific local geometric characteristics (sloped or recessed shape) that are different from the main winding portion. This local quality change creates a favorable zone that guides the wire distal end without causing abrasion, while maintaining the overall winding functionality.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of preventing the wire end from moving by constraining it directly, the design inverts the approach by providing a dedicated retreat space that invites the wire end to move into. This inverted thinking allows free movement while preventing harmful contact through positive guidance into a safe zone.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS12454243B2Webbing take-up device

Publication Date: 2025.10.28 KK TOKAI RIKA DENKI SEISAKUSHO

AI summary

A webbing take-up device includes: a spool that enables pull-out and take-up of a webbing; a rotor disposed opposite from the spool, rotation of the rotor being impeded at a time of emergency; a wire of which a proximal end portion is retained at the rotor, at least a distal end portion of the wire being retained at the spool, the wire being disposed between the rotor and the spool, wherein the webbing is pulled out at a time of emergency of a vehicle, the wire being deformed and being wound onto a winding portion of the spool; and a retreat portion provided at the winding portion, the distal end portion of the wire being disposed at the retreat portion in a case in which the wire is wound onto the winding portion.