Webbing Take-up Device Force Limiter Load Adjustment
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Solution Overview
Problem
Existing webbing take-up devices require multiple components, including body weight sensors and collision sensors, to adjust the force limiter load, leading to an increase in the number of components and complexity.
Innovation Solution
A webbing take-up device with a spool, lock section, energy absorption member, and force limiter load adjustment mechanism that adjusts the pressing force of the energy absorption member based on the remaining take-up amount of webbing, allowing for force limiter load adjustment without additional sensors or electric actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If body weight sensor and collision sensor are added to adjust force limiter load, then the force limiter load adjustment precision is improved, but the device complexity increases
Solution Approach 1:
The spool itself serves as the sensing element by directly detecting the take-up amount of webbing through its rotation. This self-service approach eliminates the need for separate body weight sensors and collision sensors, achieving force limiter load adjustment while reducing device complexity
Solution Approach 2:
The spool performs multiple functions: it not only winds the webbing but also serves as the detection element for determining the take-up amount. This multi-functionality integrates the sensing capability into an existing component, avoiding additional sensors and reducing overall device complexity
2Manufacturing precision
If multiple sensors and ECU are added to calculate webbing pull-out load, then the force limiter load adjustment accuracy is improved, but the number of components increases
Solution Approach 1:
The detection function is extracted from separate sensors and integrated directly into the spool structure. The spool's rotation directly reflects the take-up amount, eliminating the need for independent sensing components and reducing the total number of parts
Solution Approach 2:
The spool combines the winding function and detection function into a single component. By merging these functions, the patent avoids adding separate sensors and ECU, thereby reducing component quantity while maintaining adjustment accuracy
3Force
If the energy absorption member pressing force is increased to raise force limiter load, then the force limiter load is improved, but the spool rotation is overly restricted
Solution Approach 1:
The pressing force of the energy absorption member is made dynamic rather than fixed. It automatically adjusts based on the take-up amount detected by the spool, allowing the system to provide appropriate resistance at different stages of webbing deployment
Solution Approach 2:
The pressing force parameter is changed according to the take-up amount. As the spool rotates and detects webbing retraction, the pressing force is adjusted accordingly, enabling the force limiter load to adapt to different operational conditions without overly restricting spool rotation
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
Enables adjustment of the force limiter load according to the occupant's build without increasing the number of components, providing effective load management during vehicle emergencies while reducing the device's complexity and size.
Implementation Method 1
the wire extending out from the housing shaft toward the pulley is plastically deformed by an energy absorption section
Implementation Method 2
the wire is taken up onto the latch plate while being plastically deformed in the energy absorption section. This thereby absorbs shock energy
Data Source
AI summary
A webbing take-up device includes a spool that takes up a webbing worn by an occupant, and that is rotated in a pull-out direction due to the 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 further includes an energy absorbing wire that undergoes deformation so as to permit pull-out direction rotation of the spool at or above a force limiter load when the lock base has limited pull-out direction rotation of the spool, and a second force limiter mechanism that adjusts the pressing force of the energy absorbing wire according to a remaining take-up amount of the webbing on the spool.