Webbing Take-Up Device Axial Wire Guide and Lever Mechanism
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Solution Overview
Problem
Existing webbing take-up devices face challenges in taking up energy absorption members without axial direction overlap and in minimizing deformation of energy absorption members when a force limiter load is not desirable.
Innovation Solution
A webbing take-up device design that includes a spool with a torsion shaft and a second force limiter mechanism featuring a wire guide and lever system, allowing the energy absorption member to pass through a wider pass-through portion or be deformed by convex portions only when a force limiter load is generated, thereby minimizing deformation when it is not desirable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the energy absorption member is taken up onto the winder section after passing through the energy absorption section, then the deformed wire is taken up, but the wire may be overlapped in the axial direction
Solution Approach 1:
The patent introduces a guide member that redirects the energy absorption member from a direct radial path to a path that includes an axial component. The guide member is positioned at a location where it can guide the member along its length in the axial direction, preventing overlap by utilizing the axial dimension as an additional degree of freedom in the take-up path.
2Force
If the pressing face presses the energy absorption member during take-up, then force limiter load is generated, but deformation occurs when force limiter load is not desirable
Solution Approach 1:
The pressing face is designed to be movable rather than fixed, allowing it to dynamically adjust its position and pressing force. The pressing face can move in the radial direction to engage or disengage from the energy absorption member based on operational conditions, enabling the system to switch between force limiter modes and normal take-up modes without permanent deformation.
Solution Approach 2:
The patent introduces a cam mechanism as an intermediary between the rotational motion of the spool and the pressing face. The cam converts rotational motion into radial motion of the pressing face, allowing indirect control of the pressing action. This intermediary mechanism enables precise control of when and how the pressing face engages the energy absorption member, preventing unwanted deformation.
3Force
If the wire guide is positioned to deform the energy absorption member, then force limiter function is achieved, but the member cannot pass through without deformation when not needed
Solution Approach 1:
The wire guide is designed with movable components that can change its geometry or position dynamically. The guide member can shift between a deforming configuration (when force limiter function is needed) and a non-intrusive configuration (when normal operation occurs), allowing the system to adapt its behavior based on operational requirements.
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 takes up webbing without axial direction overlap and suppresses energy absorption member deformation when a force limiter load is not needed, while allowing deformation when required, enhancing load distribution and kinetic energy absorption.
Implementation Method 1
a torsion shaft (18) configured as a force limiter mechanism
Implementation Method 2
the wire extending out from the housing shaft toward the pulley is plastically deformed by an energy absorption section
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A webbing take-up device includes a spool that is rotated in a pull-out direction by a webbing being pulled out and a lock base that limits pull-out direction rotation of the spool in a vehicle emergency. The webbing take-up device also includes a wire shaped energy absorbing wire that is deformed so as to permit pull-out direction rotation of the spool at or above a force limiter load after the lock base has limited pull-out direction rotation of the spool, a winder section to which one end of the energy absorbing wire is anchored and that is rotated so as to take up the energy absorbing wire, and a wire guide and a lever that press and deform the energy absorbing wire at position offset in the axial direction of the winder section with respect to a location where the energy absorbing wire is anchored to the winder section.