Webbing Retract Restriction Weight Prevents End-Lock
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Solution Overview
Problem
Existing webbing retracting devices often enter an 'end-lock state' after taking up a webbing belt, where the reel shaft cannot rotate in the pull-out direction, making it difficult to retrieve the webbing belt.
Innovation Solution
A webbing retracting device with a spool that includes a rotational body, a lock member, a rotation detection member, and a restriction unit. The rotation detection member activates the lock member when the rotational body rotates in the pull-out direction at a predetermined velocity, and the restriction unit prevents the detection member's displacement due to rebound, thereby preventing the end-lock state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lock mechanism is configured to restrict rotation of the reel shaft in the pull out direction during vehicle deceleration, then the reliability of the seat belt system is improved, but the reel shaft may enter an end-lock state after taking up the webbing belt, making it difficult to retrieve the webbing belt
Solution Approach 1:
The rotation detection member is designed to dynamically respond to the rotational speed of the reel shaft, activating the lock member only when a predetermined rotational velocity threshold is exceeded. This dynamic activation prevents unintended locking during normal operation while ensuring locking during sudden deceleration events, thereby resolving the contradiction between reliability and ease of operation.
Solution Approach 2:
The invention changes the parameter of rotational velocity detection to control lock activation. By monitoring the rotational speed of the reel shaft and comparing it against a predetermined threshold, the system intelligently determines when to activate the lock mechanism, preventing end-lock state while maintaining safety during actual deceleration events.
2Reliability
If the restriction unit is added to prevent rebound-induced lock activation, then false end-lock state is prevented, but the device complexity increases
Solution Approach 1:
The restriction unit is merged with the existing lock mechanism structure, integrating the false-lock prevention function into the current mechanical assembly. This combining approach adds the necessary restriction capability while minimizing the increase in overall device complexity by sharing structural elements and space with existing components.
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
The device effectively prevents the end-lock state by allowing easy retrieval of the webbing belt after taking up, ensuring smooth operation during vehicle deceleration and reducing component complexity.
Implementation Method 1
The deceleration detecting means is provided with an inertial body that moves with inertia when a vehicle suddenly decelerates
Implementation Method 2
This inertial body is connected to the lock gear by a spring, but when the reel shaft together with the lock gear suddenly rotates in the pull out direction, a rotational lag occurs of this inertial body against the biasing force due to the spring
Implementation Method 3
a friction spring (112) that generates a frictional force against the gear ring (70)
Data Source
AI summary
A webbing retracting device that may prevent entering of an end-lock state when a spool rotates in the pull out direction on rebound just after completion of taking up of the webbing belt. A restriction weight is provided on a V gear. The restriction weight moves in the pull out direction relative to the V gear by acceleration when the V gear is rotated in the take up direction, and furthermore, the restriction weight pivots about a support pin under centrifugal force due to rotation of the V gear and attains a contact position. In such a state, even if the inertial mass attempts to displace toward the lock activation direction, the restriction weight interferes with the inertial mass and restricts displacement of the inertial mass toward the lock activation direction.