Webbing Take-Up Device Engagement Retention via Switch Pawl Rotation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing webbing take-up devices in vehicles require complex configurations and increased parts and processes for attachment, leading to poor attachability due to the need for elastic deformation of engagement portions, which complicates the engagement between the claw portion and the support body.
Innovation Solution
A webbing take-up device design that includes a spool, a lock mechanism, a switch member, a window portion, and an engagement portion, where the switch member rotates to switch the lock mechanism between actuated and actuatable states without requiring elastic deformation, allowing a larger facing area between the support body and engagement portion without impairing attachability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bush is used to retain the lever on the pivot support shaft, then the lever is prevented from being taken off, but the number of parts and attachment processes increase
Solution Approach 1:
The retention function previously performed by a separate bush component is merged into the pivot support shaft structure itself. The pivot support shaft is designed with a retained portion that directly engages with the lever, eliminating the need for a separate bush component while maintaining the retention function.
Solution Approach 2:
The bush component is extracted/removed from the assembly. Instead of using a separate bush to retain the lever, the pivot support shaft is modified to include the retention function directly, thereby removing the unnecessary component and simplifying the overall structure.
2Area of stationary object
If the engagement allowance between the claw portion and support body is enlarged, then the facing area is increased, but the claw portion becomes difficult to pass through the window portion
Solution Approach 1:
The engagement portion is designed to approach the regulation wall from a different spatial direction (through the window portion from the distal end side) rather than from the lateral side. This dimensional change in the engagement approach allows for a larger effective facing area while maintaining ease of attachment, as the engagement portion can pass through the window portion without requiring excessive lateral clearance.
3Reliability
If elastic deformation is required for attachment, then the engagement portion can be retained, but the attachment process becomes complex
Solution Approach 1:
The pivot support shaft includes an urging portion that automatically urges the engagement portion toward the regulation wall without requiring external elastic deformation or complex attachment processes. This self-service mechanism ensures reliable engagement retention while simplifying the attachment process, as the engagement portion is passively positioned by the urging portion rather than requiring active elastic deformation.
Data Source
AI summary
In a webbing take-up device, an open portion is formed in the other side, in a direction about a rotational axis of a switch pawl, of a sensor holder. In a state where an engagement piece is positioned on the outside of the open portion, the switch pawl is rotated about a shaft to cause the engagement piece to enter in a window portion, so, a distal end of the engagement piece, bent in a hook shape, faces to a regulation wall in an axial direction of the shaft. It is not necessary to elastically deform the engagement piece when bringing the regulation wall and the engagement piece into facing. Therefore, the engagement allowance in the engagement piece with the regulation wall can be enlarged and the distal end of the engagement piece can be prevented from crossing over the regulation wall and moving toward the shaft side.