Buckle Pretensioner Guide Rail for Submarine Phenomenon
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Solution Overview
Problem
Existing seat belt systems often fail to effectively restrain vehicle occupants during sudden deceleration, particularly when occupants are seated in various postures, leading to discomfort and the 'submarine phenomenon' where the occupant slides under the seat belt.
Innovation Solution
A buckle pretensioner system that includes a buckle, a pulling device, and a guide device, which actuates to pull the buckle in the occupant's restraining direction and guide it to a lumbar region-corresponding position, ensuring proper belt engagement and restraint without reducing seat recline angle or increasing seat cushion hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reclinable angle of the seat is reduced to prevent excessive reclining, then the lumbar region is better positioned for belt restraint, but the comfort when seated is reduced
Solution Approach 1:
The buckle is designed to move dynamically between different positions (ordinary engagement position and lumbar region-corresponding position) based on vehicle deceleration conditions. During normal operation, the buckle remains at the ordinary position for comfort. During sudden deceleration, the guide device redirects the buckle to the lumbar region position for effective restraint, thus achieving both comfort and reliability
Solution Approach 2:
The guide device is pre-configured with a predetermined path that includes a downward portion and a rearward portion, positioning the buckle in advance at the optimal location (lumbar region) before the actual restraint force is applied during collision, ensuring immediate effectiveness without requiring seat configuration changes
2Reliability
If the webbing belt is pulled back by the pretensioner system during sudden deceleration, then the occupant restraint is improved, but a large load is applied to the occupant when the belt does not catch on the proper position
Solution Approach 1:
The guide device acts as an intermediary mechanism between the pulling device and the buckle. It controls the movement path of the buckle, ensuring that during sudden deceleration, the buckle is guided to the lumbar region-corresponding position before the webbing belt is pulled back. This intermediate guidance ensures proper belt positioning and prevents excessive load on the occupant
3Reliability
If the hardness of the front part of the seat cushion is increased to prevent lumbar region sliding, then the belt positioning is improved, but the comfort when seated is reduced
Solution Approach 1:
The invention replaces the mechanical approach of increasing seat cushion hardness with a mechanical guidance system (guide device with predetermined path). Instead of relying on seat structure to position the buckle, the guide device actively guides the buckle along a predetermined path to the lumbar region position, achieving proper belt positioning without compromising seat comfort
Data Source
AI summary
A buckle pretensioner system includes a substantially L-shaped rail for guiding a buckle body of a buckle from a position where the buckle body engages with a tongue plate to a position corresponding to a lumbar region of a vehicle occupant. When a vehicle disposed with the buckle pretensioner system undergoes a sudden deceleration, a piston inside a cylinder is moved in a frontward direction of the vehicle by gas generated by the actuation of a gas generator, a buckle stay is pulled by a wire coupled to the piston, and the buckle stay is moved along the shape of the rail. As a result, the buckle body supported by the buckle stay pivots from the position where the buckle body engages with the tongue plate to a vehicle occupant restraining position of a webbing belt, and then is pulled to the lumbar region-corresponding position.