Vehicle Headrest Rod Anti-Extraction Notch Design
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Solution Overview
Problem
Existing motor vehicle seat headrest systems fail to securely maintain the headrest in place during violent shocks, particularly when the impact is decentralized, leading to a risk of ejection due to axial rotation of the headrest rod, which compromises passenger safety.
Innovation Solution
The system incorporates a headrest with parallel rods connected by a cross member, featuring an anti-extraction notch with a main chamfer and secondary chamfers, along with radial sliding sleeves and an actuating spring, ensuring the edge of the drawer can insert into the notch even during axial rotation, preventing ejection and maintaining the headrest in a safe position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple anti-extraction notch with a single chamfer is used, then the structure is simple and easy to manufacture, but the headrest rod can rotate axially during violent impacts, causing the drawer to misalign with the notch and risking ejection
Solution Approach 1:
The single chamfer is segmented into multiple chamfers (first chamfer, second chamfer, third chamfer) arranged at different angular positions around the rod. This segmentation allows the drawer to engage with at least one chamfer regardless of the rod's rotational position during impact, preventing misalignment and ejection while maintaining structural simplicity.
Solution Approach 2:
The multiple chamfers are designed with different angular positions to accommodate dynamic rotational movement of the rod during violent impacts. The drawer can dynamically engage with different chamfers depending on the rod's instantaneous position, ensuring continuous security without requiring a complex locking mechanism.
2Reliability
If the drawer edge is designed to engage precisely with the anti-extraction notch at a fixed position, then locking is secure under normal conditions, but axial rotation of the rod during impact causes misalignment and loss of locking
Solution Approach 1:
The chamfers are arranged asymmetrically at different angular positions around the rod rather than being uniformly distributed. This asymmetric arrangement provides optimal engagement points that accommodate the specific rotational directions and magnitudes expected during vehicle accidents, enhancing both locking security and rotation tolerance.
Solution Approach 2:
The multiple chamfers serve multiple functions: they provide locking engagement under normal conditions, accommodate axial rotation during impacts, and ensure the drawer can always find an engagement point. This multi-functionality allows a single chamfer structure to handle both precise locking and rotational adaptability.
3Reliability
If secondary chamfers are added to the main chamfer, then the drawer can remain engaged during rod rotation, but the manufacturing complexity increases
Solution Approach 1:
The chamfer structure is segmented into multiple simpler chamfers rather than one complex chamfer. Each chamfer can be manufactured using standard machining operations, and their collective arrangement provides the rotational engagement capability without requiring complex multi-axis machining or specialized tooling.
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
This configuration effectively secures the headrest in place during accidents, minimizing the risk of ejection and ensuring passenger safety by allowing the drawer's edge to slide into the anti-extraction notch, even when the rod rotates, thus maintaining the headrest's position.
Implementation Method 1
an actuating spring for said slide towards said first rod so as to allow the progressive insertion of said edge into said notch when said first rod is actuated to slide upwards
Implementation Method 2
said edge sliding against said main chamfer until its insertion into said notch
Data Source
Figure 1~2a
Figure 2b~3b
AI summary
The invention relates to a system comprising a first rod (3a) provided with an anti-extraction notch (5a) having a lower serrated face (6) and an upper locking face (7), said first rod having a main chamfer (8) opening onto said upper face, said system comprising a first sleeve provided with a radially sliding slide and having a serrated edge arranged to insert into said notch when they are opposite each other, said edge sliding against said main chamfer until its insertion into said notch, said main chamfer being provided at each of its ends with a respective secondary chamfer (13a, 13b), so that said edge can slide against one of said secondary chamfers until its insertion into said notch in the event of rotational movement of said first rod to either side of its nominal position along the extension axis (14) of said first rod