Webbing Take-up Device with Integrated Force Limiter Load Switching
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Solution Overview
Problem
Webbing take-up devices have complex structures due to the need for separate actuators for force limiter load switching and pre-tensioner mechanisms, which increases complexity and potential for errors in vehicle emergency situations.
Innovation Solution
A webbing take-up device with integrated mechanisms that utilize a spool, pre-tensioner, lock, force limiter, and force limiter load switching mechanisms, where the pre-tensioner actuation force inputs the force limiter load switching mechanism to switch the force limiter load value without additional actuators, allowing for reduced structural complexity and adaptive load settings based on occupant build and emergency conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate actuators are provided for force limiter load switching and pre-tensioner mechanisms, then each mechanism can operate independently and reliably, but the device structure becomes complex
Solution Approach 1:
The patent combines the pre-tensioner mechanism and force limiter load switching mechanism into a single integrated assembly. The pre-tensioner actuator directly drives both the spool for webbing take-up and the load switching mechanism through mechanical coupling, eliminating the need for separate actuators while maintaining operational reliability of both functions
Solution Approach 2:
The pre-tensioner actuator is designed to perform multiple functions: it simultaneously drives the spool for rapid webbing take-up during collision and switches the force limiter load value through mechanical coupling. This multi-functional design reduces the total number of actuators while ensuring both pre-tensioning and load switching operations are reliably executed
2Adaptability or versatility
If additional actuators are added for force limiter load switching, then load value switching can be precisely controlled, but the device complexity and potential for errors increase
Solution Approach 1:
The force limiter load switching mechanism is mechanically integrated with the pre-tensioner actuator. The actuator's motion is mechanically coupled to switch between high and low load values, eliminating the need for additional actuators while maintaining precise load value control adaptability
Solution Approach 2:
The pre-tensioner actuator automatically performs the load switching function as part of its own operation. The mechanical coupling ensures that when the actuator drives the spool for webbing take-up, it simultaneously triggers the load switching mechanism, making the system self-sufficient without requiring external or additional actuators
Data Source
AI summary
An increase in structural complexity is suppressed in a webbing take-up device provided with a force limiter load switching mechanism and a pre-tensioner mechanism. The webbing take-up device includes a spool that takes up a webbing, a pre-tensioner mechanism that takes up the webbing onto the spool by rotating the spool in the take-up direction in a vehicle emergency, and a lock mechanism that restricts pull-out direction rotation of the spool in a vehicle emergency. The webbing take-up device further includes a force limiter mechanism that permits pull-out direction rotation of the spool at a force limiter load or greater when the lock mechanism has restricted pull-out direction rotation of the spool, and a force limiter load switching mechanism that switches a force limiter load value by being input with a portion of an actuation force that actuates the pre-tensioner mechanism.