Vehicle Safety Device Dynamic Load Limiting via Electromagnetic Feedback
Solution Overview
Problem
Conventional load limiters in vehicles fail to provide optimized performance at speeds other than specific design speeds, leading to unreliable operation and inadequate protection for occupants during collisions due to phenomena like overshoot and lock dip.
Innovation Solution
A safety device featuring a roller that rotates with seat belt webbing, generating electric current to produce a magnetic force, which creates a resistance force to control the roller's rotation, allowing the reference load for webbing release to vary with collision speed, comprising an electric generator, magnetic force generator, and resistance force generator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional load limiter is mounted to meet specific speed regulations, then it provides proper operability at that specific speed, but it fails to provide optimized performance at speeds other than the specific speed
Solution Approach 1:
The load limiter transitions from a static mechanism designed for a single speed to a dynamic system that automatically adjusts its characteristics based on collision speed. The roller's rotational inertia and the magnetic force generator's variable magnetic force enable the system to adapt its load-limiting behavior dynamically, providing optimized performance across different collision speeds rather than being fixed for one specific speed.
Solution Approach 2:
The system changes its operational parameters based on collision speed. As the roller rotates at different speeds corresponding to different collision velocities, the magnetic force generator produces varying magnetic forces that adjust the reference load for webbing release. This parameter change enables the load limiter to provide appropriate protection across a range of speeds rather than being optimized for only one specific speed.
2Device complexity
If the reference load for webbing release is fixed, then the mechanism is simple, but it causes overshoot or lock dip phenomena that reduce reliability
Solution Approach 1:
The system incorporates feedback through the roller's rotation speed detection. As the webbing pulls the roller, the rotation speed provides information about the collision force and speed. The magnetic force generator responds to this feedback by adjusting the magnetic force accordingly, which stabilizes the webbing release process and prevents overshoot or lock dip phenomena that would occur with a completely fixed reference load system.
Solution Approach 2:
The patent replaces part of the traditional mechanical reference load determination system with an electromagnetic system. Instead of relying solely on fixed mechanical springs or levers that cause abrupt releases, the magnetic force generator provides a more controllable and stable force that adjusts with roller speed, eliminating the harsh mechanical feedback that causes reliability issues.
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 provides a stable and optimized load limiter mechanism that adjusts the reference load based on collision speed, enhancing occupant protection by preventing abrupt movements and ensuring optimal functionality across varying collision speeds.
Implementation Method 1
an electric generator configured to generate electric current by the rotation of the roller
Implementation Method 2
a magnetic force generator configured to generate a magnetic force via the electric current generated by the electric generator
Implementation Method 3
a resistance force generator configured to provide a resistance force to the rotation of the roller based on a shear force altered by the magnetic force generated by the magnetic force generator
Data Source
AI summary
A safety device for a vehicle, which provides a more simple optimized mechanism to function as a load limiter having stable operation characteristics, and allows a reference load for releasing the webbing to vary depending on a change in collision speed, thereby providing increased protection to an occupant. More specifically, the safety device includes a roller, an electric generator, a magnetic force generator and a resistance generator. The roller comes in contact with a webbing and is configured to rotate with movement of the webbing. The electric generator generates electric current via the rotation of the roller, and the magnetic force generator generates a magnetic force via the electric current generated by the electric generator. The resistance force generator provides a resistance force to the rotation of the roller based on a shear force altered by the magnetic force generated by the magnetic force generator.