Vehicle Headrest Spindle Locking via Asymmetric Rib and Cut-off Corner

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Solution Overview

Problem

Conventional headrest assembly for motor vehicle seats requires force-fit pins for locking spindles, which can lead to damage if incorrectly assembled, and lacks a straightforward method to verify proper assembly.

Innovation Solution

A spindle assembly system featuring a cut-off corner and a horizontal rib that cooperates with a deformable tab to provide a mistake-proof guide for engagement and locking, allowing easy detection of incorrect assembly through visual or automated means.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If force-fit pins are used to lock spindles in the headrest body, then the spindles can be securely locked, but the assembly process becomes complex and the plastic frame may be damaged if incorrectly assembled

Engineering Contradiction:

Improvesecure locking of spindlesVSAvoidassembly process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The spindle features an asymmetric cut-off corner that must align with a corresponding asymmetric rib in the housing. This asymmetric geometry provides a built-in guide that directs the spindle into the correct position during assembly, eliminating the need for complex force-fit pin mechanisms while ensuring secure locking through the rib-spindle interface

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The cut-off corner and rib combination creates a self-aligning and self-locking mechanism. The asymmetric cut-off corner automatically guides the spindle into the correct orientation, and the rib engages with the spindle to provide secure locking without requiring additional pins or complex assembly procedures

Inventive Principle:

Principle #25Self-service

2Reliability

If conventional assembly methods are used, then spindles can be locked in place, but it is difficult to verify whether the assembly is correct

Engineering Contradiction:

Improvesecure locking of spindlesVSAvoidverification of proper assembly

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The cut-off corner provides a visible geometric feature that changes the appearance of the assembled headrest. When the spindle is correctly assembled, the cut-off corner aligns with the rib in a specific orientation, creating a distinctive visual pattern that allows easy verification of proper assembly without requiring complex inspection procedures

Inventive Principle:

Principle #32Color changes

3Reliability

If force-fit pins are used for locking, then secure locking is achieved, but the risk of damage to the plastic frame increases

Engineering Contradiction:

Improvesecure locking of spindlesVSAvoiddamage to plastic frame

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention removes the force-fit pin component entirely from the assembly system. The secure locking function is achieved through the rib engaging with the spindle's cut-off corner geometry, eliminating the need for separate locking pins that could damage the plastic frame during installation or if misaligned

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS8820840B2Headrest for motor vehicle seat

Publication Date: 2014.09.02 FAURECIA SIEGES D AUTOMOBILE SA

AI summary

A headrest for a motor vehicle seat comprises at least one spindle for assembling the headrest in a backrest of the seat; and a body provided with at least one housing in the shape of a sleeve for receiving one end of said spindle, the spindle comprising, in an upper portion, a shoulder capable of cooperating with a horizontal rib, protruding inside of a housing of the body, to lock any translation of the spindle in its housing.