Webbing Take-up Device Axial Gap Inspection Opening
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Solution Overview
Problem
Existing vehicle seatbelt retractor designs make it difficult to assess the gap between ratchet teeth of a lock gear and lock teeth of a lock plate from a face-on perspective due to the components' orientation, requiring diagonal assessment which is cumbersome.
Innovation Solution
A webbing take-up device with a lock mechanism featuring a lock gear and lock plate, where a pair of leg plates are positioned to form an opening portion allowing direct assessment of the gap between ratchet teeth and lock teeth along the take-up shaft axial direction, and extending portions with cut-out portions to facilitate this view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the lock mechanism components are disposed at the side of the take-up shaft, then the structural integrity and compactness are maintained, but the gap between ratchet teeth and lock teeth cannot be assessed from face-on direction
Solution Approach 1:
The patent introduces a new spatial dimension by forming an opening portion through the leg plate, enabling face-on (axial direction) observation of the gap between ratchet teeth and lock teeth. This transforms the inspection approach from diagonal/side viewing to direct axial viewing, resolving the measurement difficulty without altering the side-mounted component arrangement.
2Productivity
If diagonal direction assessment is used to evaluate the gap, then the existing component layout is maintained, but the assessment becomes difficult and time-consuming
Solution Approach 1:
The patent extracts a viewing path through the leg plate by forming an opening portion, separating the inspection function from the structural components. This allows direct visual access to the gap between teeth along the axial direction, eliminating the need for complex diagonal assessment and significantly improving inspection efficiency.
3Measurement precision
If the opening portion is formed at the leg plate, then direct face-on gap assessment is enabled, but the leg plate structure is modified
Solution Approach 1:
The leg plate is segmented by forming an opening portion through it, creating a through-hole structure that allows axial viewing of the lock mechanism. This segmentation approach enables precise gap measurement while maintaining the overall structural integrity of the leg plate, and can be implemented through standard manufacturing processes.
Data Source
AI summary
A webbing take-up device including: a take-up shaft on which a webbing is taken up; a lock mechanism including a lock gear disposed at one axial direction end portion of the take-up shaft and formed with ratchet teeth, and a lock plate formed with lock teeth engaging with the ratchet teeth; and a frame including a pair of leg plates disposed at both axial direction end portions of the take-up shaft, an opening portion being formed at a leg plate of the pair of leg plates disposed further to the other axial direction end portion of the take-up shaft than the ratchet teeth and the lock teeth, and the opening portion passing through the leg plate at a position that faces towards a range including a mutual engagement position between the ratchet teeth and the lock teeth and the periphery of the engagement position along the take-up shaft axial direction.