Webbing Take-Up Device Inertial Locking Mechanism
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Solution Overview
Problem
Existing webbing take-up devices face issues with unwanted locking of spool rotation, require a larger physical size due to multiple locking units, and have durability concerns from repeated actuation.
Innovation Solution
A webbing take-up device with a rotatable locking section that engages with a fixed locking section via an inertial force or magnetic force, utilizing a displacement section and restricting section to lock spool rotation only during vehicle emergencies, while minimizing component count and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solenoid-based anchoring claw mechanism is used to lock spool rotation, then the locking function is achieved, but unwanted locking occurs due to electrical system faults or poor terminal connections
Solution Approach 1:
The patent replaces the solenoid-based electromagnetic locking mechanism with an inertial force-based mechanical locking mechanism. The rotatable locking section utilizes inertial force generated during vehicle emergencies (deceleration, collision, overturning) to automatically engage with the fixed locking section, eliminating dependence on electrical systems and preventing unwanted locking due to electrical faults
Solution Approach 2:
The locking mechanism is designed to automatically activate based on the vehicle's motion state without requiring external control signals. The inertial force generated during emergencies naturally drives the rotatable locking section to engage with the fixed locking section, enabling the system to self-activate based on physical conditions rather than electrical commands
2Reliability
If multiple locking units (first and second locking units) are provided to ensure locking even if one fails, then reliability is improved, but the physical size and number of configuration components increase
Solution Approach 1:
The patent merges the functions of multiple locking units into a single integrated locking mechanism. The rotatable locking section is designed to engage with multiple positions on the fixed locking section, providing redundant locking capability within a single component structure, thereby reducing the total number of components while maintaining reliability
Solution Approach 2:
The fixed locking section is designed with multiple engagement positions that can interact with the rotatable locking section. This single fixed locking section performs multiple locking functions simultaneously, replacing the need for separate first and second locking units, thereby reducing device complexity while ensuring reliable locking
3Adaptability or versatility
If a locking mechanism is provided that can actuate repeatedly during continued use of the vehicle, then emergency locking capability is ensured, but durability of the locking mechanism deteriorates
Solution Approach 1:
The patent replaces the solenoid-based electromagnetic mechanism with a passive inertial force-based mechanical mechanism. This eliminates the wear and tear associated with electromagnetic coils and electrical connections, significantly improving the durability of the locking mechanism for repeated actuation during continued vehicle use
Solution Approach 2:
The locking mechanism uses simple mechanical components with no electrical parts that can fail. The inertial force-based engagement mechanism is designed to withstand repeated actuation without degradation, effectively creating a durable, long-lasting locking system that does not rely on consumable electrical components
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 solution effectively suppresses unwanted locking of spool rotation, reduces device size, and enhances durability by ensuring the locking mechanism engages only when necessary, thereby improving occupant safety and device reliability.
Implementation Method 1
A restricting force of the rotatable locking section by the restricting section is set such that the rotatable locking section is displaced toward the fixed locking section by an inertial force that spins the rotatable locking section about its own center of rotation when the displacement section is deactivated and the spool has been rotated in the pull-out direction with an angular acceleration greater than a predetermined angular acceleration.
Data Source
AI summary
The rotatable locking section engages with the fixed locking section resulting in pull-out direction rotation of the spool being locked. The webbing take-up device includes a permanent magnet and an electromagnet that restrict displacement of the rotatable locking section toward the fixed locking section, and that are actuated in a vehicle emergency so as to displace the rotatable locking section toward the fixed locking section. A restricting force of the rotatable locking section by the permanent magnet and the electromagnet is set such that the rotatable locking section is displaced toward the fixed locking section by an inertial force that spins the rotatable locking section about its own center of rotation when the electromagnet is deactivated and the spool has been rotated in the pull-out direction with an angular acceleration greater than a predetermined angular acceleration.