Webbing Take-Up Device Stopper Offset Design
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Solution Overview
Problem
Existing webbing take-up devices face issues with stoppers being inadvertently moved by the urging force of power springs, leading to potential misalignment and safety risks due to the linear shape of stopper ends and the design of cutout portions.
Innovation Solution
A webbing take-up device design featuring a spool, adapter, and urging member where the adapter's rotation is regulated by a stopper inserted into an offset insertion portion, with wall portions positioned to reduce the extrusion force, preventing stopper movement by offsetting the center line of the wall portions relative to the rotation center and maintaining the urging force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If both width-direction ends of the stopper are formed in a linear shape, then stopper removal is simplified, but the urging force may act to extrude the stopper from the cutout portion
Solution Approach 1:
The linear shape of the stopper ends is maintained for ease of removal, while the asymmetric insertion portion geometry compensates for the potential extrusion issue. The offset center line of the wall portions creates a geometric constraint that prevents stopper extrusion despite the linear end shape.
Solution Approach 2:
The insertion portion serves as an intermediary that allows the stopper to have a simple linear shape for easy removal, while simultaneously preventing extrusion through its offset wall portion geometry. It mediates between the simplicity of linear ends and the stability requirement.
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 effectively prevents stopper movement caused by the urging force, ensuring stable operation and safety by reducing the extrusion component of the pressing force, thus maintaining the urging force and preventing unintended stopper displacement.
Implementation Method 1
an urging member whose one end is coupled to the adapter, that urges the adapter in the take-up direction with an urging force, the urging force being increased by the adapter being rotated in a drawing-out direction opposite to the take-up direction
Data Source
AI summary
In an insertion hole formed in an adapter, a side wall which presses an insertion piece of a stopper with an urging force of a spiral spring has a wall surface parallel to a virtual straight line passing a center of the adapter and positioned on the virtual straight line. Thus, a direction which the wall surface of the side wall presses the insertion piece of the stopper is along a facing direction which the side wall and another side wall face each other, and is not inclined outward in a radial direction of the adapter with respect to the facing direction. Thereby, a pressing force applied from the wall surface of the side wall to the insertion piece of the stopper does not cause the insertion piece to be extruded from the insertion hole. Thus, insertion state of the insertion piece to the insertion hole can be satisfactorily maintained.