Vehicle Seat Back Detachment Structure for Rear-Impact Head Support
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Solution Overview
Problem
Conventional vehicle seat headrest drives are complex, increasing seat weight and cost, and fail to effectively support the occupant's head during rear impacts due to ineffective shock-absorbing mechanisms, especially when a large load is applied to the lower half of the seat back.
Innovation Solution
A vehicle seat design featuring a seat back frame with side wires, a plane spring structure, and detachable connection wires that disengage under load, restricting rearward movement and allowing quick headrest contact, with U-shaped hooks at the ends of the connection wires detaching between 150 kgf and 800 kgf to reduce seat back movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional headrest drive is used to support the occupant's head during rear impact, then head support function is improved, but seat weight and structure complexity increase
Solution Approach 1:
The patent extracts the essential function of head support during rear impact from the complex headrest drive mechanism. By removing the motor, control system, and complex linkage, and retaining only the critical plane spring structure with detachable connection wires, the invention achieves head support function with dramatically reduced complexity and weight
Solution Approach 2:
The connection wires are designed as disposable sacrificial elements that detach under collision load. These simple, inexpensive wire connections with detachable portions (hooks or loops) replace the complex reusable headrest drive mechanism, providing effective head support through controlled detachment rather than complex active control
2Reliability
If a headrest drive with shock-absorbing part is used, then shock absorption is improved, but the shock-absorbing part cannot function effectively when large load is applied to the lower half of seat back
Solution Approach 1:
The patent segments the connection between seat back frame and plane spring structure into multiple detachable connection wires distributed at different locations. This segmentation allows the system to respond to loads applied at various positions on the seat back, including the lower half, by having the appropriate connection wires detach to provide shock absorption adapted to the specific load position and magnitude
3Speed
If detachable portions are designed to detach under load, then rearward movement restriction is improved, but the detachment mechanism adds complexity
Solution Approach 1:
The patent changes the mechanical parameter of the connection wires from permanently fixed to having a specific detachment force threshold. By controlling the wire diameter, material properties, and hook/loop geometry, the connection wires automatically detach when the load exceeds a predetermined value, providing speed-controlled headrest contact without complex control systems or sensors
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 design simplifies the structure, reduces the time for the occupant's head to contact the headrest, effectively stopping rearward head movement and providing equivalent head support to traditional headrest drives without increasing weight or complexity.
Implementation Method 1
a plane spring structure having horizontal wires provided between the side wires at some intervals in the vertical direction
Data Source
AI summary
A seat back has a seat back frame, a plane spring structure, and a headrest provided at the upper end of a seat back frame. The plane spring structure has left and right side wires, and horizontal wires extending in the horizontal direction. Connection wires are provided between the seat back frame and plane spring structure. First end portions and second end portions of the connection wires function as detachable portions. At least one of these detachable portions is detached from the seat back frame or plane spring structure by the load applied to the seat back, when a vehicle is bumped from behind.