Webbing Winding Device Protector Attachment
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Solution Overview
Problem
Existing webbing winding devices face difficulties in reliably holding and attaching a protector to the insertion portion due to the high deflection required for attachment, which complicates the process and makes it challenging to maintain effective protection during load applications.
Innovation Solution
A webbing winding device design featuring an annular protector with a claw and contact portion that restricts movement, where the claw's projecting amount is minimized to facilitate easier attachment, and the contact area is larger than the claw area, allowing for effective holding and protection without excessive deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the projecting amount of the flange is increased to reliably hold the protector under load, then the holding reliability is improved, but the deflection amount required for attachment increases making attachment difficult
Solution Approach 1:
The holding structure is segmented into two distinct functional elements: a claw portion for primary anchoring and a contact portion for secondary support. This segmentation allows each element to be optimized independently - the claw portion provides reliable holding under load with minimal deflection, while the contact portion provides additional support without requiring large deflection amounts for attachment.
Solution Approach 2:
Different regions of the protector's outer circumferential portion are given different properties: the claw portion has a larger projecting amount for secure anchoring, while the contact portion has a smaller projecting amount for easier attachment. This local differentiation resolves the contradiction by providing both reliable holding and ease of attachment at different locations.
2Reliability
If the protector is made to cover the entire inner circumferential portion of the insertion hole for complete protection, then the protection coverage is improved, but the device complexity increases
Solution Approach 1:
The invention extracts the essential protective function from the concept of complete coverage. Instead of requiring the protector to cover the entire inner circumferential portion, it positions the protector at the opening where it can effectively protect the webbing from contacting the insertion hole periphery. This extraction simplifies the structure while maintaining effective protection.
Solution Approach 2:
The protector is positioned in advance at the opening of the insertion hole to prevent webbing contact with the periphery before any load is applied. This preliminary positioning at the critical protection point eliminates the need for complex structures that would otherwise be required to achieve complete coverage.
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 design ensures reliable attachment and holding of the protector, reducing the deflection needed during attachment and maintaining effective protection under load conditions, such as those encountered in emergencies.
Implementation Method 1
the protector being elastically deformed, the protector covering an inner circumferential portion of the insertion hole
Data Source
AI summary
In a webbing-winding device, a tension acting on a webbing is smaller when a pretensioner-mechanism is actuated than when a force-limiter mechanism is actuated, thus, projection dimensions of a first claw and a second claw can be made smaller than projection dimensions of second contact portions. A total of contact areas of first contact portions and the second contact portions with a body portion is larger than a total of contact areas of the first claw and the second claw with the body portion. Accordingly, the first claw and the second claw are caused to insert through an insertion hole from the lower side of a stay to attach. Since the projection dimensions can be made smaller, an amount of deflection of the protector can be made smaller. Therefore, the protector can be held on the stay reliably to allow the protector to be attached to the stay easily.