Vehicle Seat Headrest Rod Locking Against Rotation and Dislodging
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Solution Overview
Problem
The existing motor vehicle seat headrest design faces issues with securing the vertical metal rods to the spacer, leading to potential dislodging and axial rotation during impacts, compromising safety due to incomplete locking in height adjustment positions.
Innovation Solution
The design incorporates elastically deformable harpoons with hooks on the lateral parts of the spacer that temporarily approximate and insert into orifices on the rods, combined with blocking elements to prevent release, ensuring secure attachment and minimizing axial rotation risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the rods are mounted from the bottom of the housing or guide block, then assembly is simplified, but perfect blocking of the rods against axial translation and rotation relative to the spacer cannot be guaranteed
Solution Approach 1:
The harpoons are pre-formed with hooks at their free ends, and the locking elements are pre-positioned on the spacer. During assembly, the harpoons are temporarily brought together, allowed to elastically return to their nominal position, and the hooks automatically engage with the orifices in the rod ends. The locking elements are then inserted to secure the harpoons in their nominal position. This preliminary preparation of components enables reliable locking while maintaining assembly simplicity.
Solution Approach 2:
The harpoons are designed with elastic deformability, allowing their shape to change during assembly. They can be temporarily brought together (changed state), inserted into the rod ends, and then elastically return to their nominal position (original state), where the locking elements secure them. This parameter change enables the harpoons to transition between assembly and locked states, resolving the contradiction between ease of assembly and blocking reliability.
2Ease of operation
If the harpoons are made elastically deformable to enable insertion, then assembly is facilitated, but the risk of axial rotation during impact remains if not properly locked
Solution Approach 1:
The locking elements are pre-positioned on the spacer before assembly. When the harpoons are inserted and elastically return to their nominal position, the locking elements are immediately inserted to engage with the harpoons and prevent axial rotation. This preliminary preparation ensures that the anti-rotation function is activated as soon as the harpoons are in place, maintaining reliability while facilitating ease of operation.
Solution Approach 2:
The locking elements act as intermediaries between the harpoons and the rod ends. They engage with the harpoons in their nominal position and prevent axial rotation, while allowing the harpoons to maintain their elastic deformability for easy insertion. This intermediary component resolves the contradiction by providing the anti-rotation function without compromising the ease of insertion.
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 enhances the safety of the headrest by securely attaching the rods to the spacer, reducing the risk of dislodging and axial rotation, thus maintaining the locking mechanism's integrity during height adjustments and impact events.
Implementation Method 1
harpoons being elastically deformable so as to be able to be brought together, the free ends of said harpoons forming hooks projecting radially outwards
Implementation Method 2
two locking elements which are inserted respectively between said harpoons of each of said lateral parts, so as to lock them in their nominal position and to prevent the release of said hooks from said orifices
Data Source
Figure 1
Figure 2~3
AI summary
Headrest (1) of a motor vehicle seat, said headrest comprising two rods (2) and a spacer (4) having downward-projecting lateral parts (5), said lateral parts fitting into the upper ends (6) of said rods, each of said lateral parts having two diametrically opposed harpoons (8) so that the fitting of said lateral part into the upper end (6) of said rod is done with temporary approach of said harpoons to each other and then elastic return to their nominal position allowing insertion of said hooks into two respective orifices (10) provided in said upper end, said spacer being provided with two locking elements (13) inserting respectively between said harpoons of each of said lateral parts, so as to lock them in their nominal position and to prevent the release of said hooks from said orifices.