Webbing Retractor Centrifugal Locking Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing webbing retractor devices often experience 'end-lock' issues where the spool cannot rotate in the pull-out direction after webbing belt retraction, making it difficult to extract the belt, due to unintended engagement of inertial bodies with ratchet teeth during reverse actions.
Innovation Solution
A webbing retractor device with a spool, a rotating body, a lock portion, and a holding portion that utilizes centrifugal force to prevent relative rotation between the spool and rotating body, ensuring the spool remains locked in the retraction direction until it fully stops, thereby preventing 'end-lock' scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lock mechanism uses inertial bodies to detect rapid deceleration and engage with ratchet teeth, then the lock mechanism can reliably restrict spool rotation in the pull-out direction during emergency braking, but the inertial body may inadvertently engage with ratchet teeth after retraction completes, causing end-lock
Solution Approach 1:
The lock mechanism is divided into separate functional components: a lock portion with lock teeth for engagement, and a holding portion with holding teeth that engage during rotation but disengage when rotation stops. This segmentation allows the holding portion to prevent end-lock while the lock portion maintains reliable locking during emergency braking.
Solution Approach 2:
The holding portion is designed to dynamically engage with the spool during rotation through centrifugal force, but automatically disengage when rotation stops. This dynamic behavior prevents the inertial body from inadvertently engaging with ratchet teeth after retraction completes, eliminating end-lock while maintaining ease of operation.
2Reliability
If the inertial body is connected to the lock gear by a spring to allow delayed rotation, then the lock gear can rotate relative to the reel shaft during rapid deceleration, but the inertial body may engage with ratchet teeth due to this delayed rotation, causing end-lock
Solution Approach 1:
The detection mechanism is segmented into a holding portion that handles normal rotation detection and a lock portion that handles emergency locking. The holding portion uses holding teeth that engage during rotation but disengage when rotation stops, preventing inadvertent lock engagement while maintaining accurate deceleration detection.
Solution Approach 2:
The holding portion acts as an intermediary between the spool rotation and the lock mechanism. It allows the spool to rotate during normal operation while preventing the lock portion from engaging unless genuine emergency deceleration occurs, thus preventing end-lock while maintaining detection accuracy.
3Reliability
If the spool rotates sharply in the pull-out direction after retraction completes, then the inertial body engages with ratchet teeth, but rotating the spool in the pull-out direction to extract the belt causes the lock mechanism to operate, resulting in end-lock
Solution Approach 1:
The holding portion is designed with holding teeth that dynamically engage during spool rotation in either direction but automatically disengage when rotation stops. This dynamic engagement-disengagement cycle allows the spool to rotate freely during belt extraction after retraction completes, preventing end-lock while maintaining reverse action detection capability.
Solution Approach 2:
The holding portion changes its engagement parameter based on rotation state: engaged during rotation (whether forward or reverse) and disengaged when rotation stops. This parameter change allows the mechanism to distinguish between active rotation (where locking may be needed) and stationary state (where locking should not occur), preventing end-lock during belt extraction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively suppresses the occurrence of 'end-lock' by ensuring the rotating body remains aligned with the spool's retraction direction, allowing smooth belt extraction without premature lock engagement.
Implementation Method 1
a holding portion that holds the rotating body due to a centrifugal force of the spool rotating in the retraction direction
Data Source
AI summary
When a spool rotates in a retraction direction, a guide pin of a lock member presses against an inner wall of a groove portion with a pressing force in the same direction as a centrifugal force. As a result, friction between an outer circumferential portion of the guide pin and the inner wall of the groove portion increases, a V-gear is held by the guide pin, and rotation of the V-gear in the retraction direction relative to the spool is suppressed. Further, the V-gear, which is pressed by a pressing force at the inner wall of the groove portion, presses against a shaft portion of a torsion shaft with a pressing force in the same direction as the above-described pressing force when the V-gear attempts to move in the direction of action of the above-described pressing force. Accordingly, friction between an inner circumferential portion of the V-gear and an outer circumferential portion of the shaft portion increases and, as a result, rotation of the V-gear in the retraction direction relative to the spool is suppressed.