Seat Belt Locking Tongue Localized Clamping Prevents Webbing Fraying
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Solution Overview
Problem
Conventional locking tongues in seat belt systems cause fraying of webbing edges due to metal clamping, which affects the strength and reliability of the belt during a vehicle crash.
Innovation Solution
A locking tongue design where the restricting portion and locking member contact the webbing at a length smaller than the webbing width, preventing edge contact and using a resin-molded locking member to minimize fraying, with a resin-covered contact area to enhance clamping performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the webbing is clamped by pressing the locking member formed of metal against the entire width area of the webbing, then the clamping performance is improved, but the fiber at the edges of the webbing may be easily broken and fraying may occur
Solution Approach 1:
The patent applies local quality by making the contact length between the locking member and webbing smaller than the webbing width, concentrating the clamping force on a specific central region while leaving the edge regions unaffected. This localized clamping approach prevents edge fraying while maintaining sufficient clamping performance for crash conditions.
Solution Approach 2:
The patent segments the webbing width into different functional zones: a central clamping zone where the locking member contacts the webbing, and edge zones that remain free from clamping forces. This segmentation allows the edge fibers to maintain their integrity while the central portion provides the necessary restraint.
2Strength
If the locking member is formed of metal to provide high strength, then the locking performance is improved, but the metal contact causes fiber breakage and fraying at the webbing edges
Solution Approach 1:
The patent uses local quality by limiting the metal locking member's contact with the webbing to a specific region that does not extend to the edges. The metal provides necessary strength for locking performance while its contact area is locally constrained to avoid damaging the vulnerable edge fibers.
3Reliability
If the restricting portion is formed to clamp the entire webbing width, then the clamping performance is improved, but the edges of the webbing come into contact with the restricting portion causing fraying
Solution Approach 1:
The restricting portion is designed with a contact length in the longitudinal direction that is smaller than the webbing width, creating a localized clamping region. This ensures that only the central portion of the webbing is clamped while the edge portions remain free from contact with the restricting portion, preventing fraying.
Data Source
AI summary
A seat belt restraint system locking tongue (10) having a locking member (30) which moves to a locked position to clamp a webbing (3) inserted in a shoulder-side webbing insertion slot (12) to restrict movement of the webbing (3). A tongue body (11) includes a restricting portion (25) near the shoulder-side webbing insertion slot (12) to clamp the webbing (3) with the locking member (30) when the locking member (3) moves to the locked position. The length in the longitudinal direction of the webbing insertion slot (12), of a portion of the restricting portion (25) that contacts the webbing (3) to clamp the webbing (3) is smaller than the width of the webbing (3). The locking tongue prevents fraying of the webbing (3) and improves the clamping performance in the event of a vehicle crash.