Headrest Locking Mechanism That Resists Collision Loosening

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Solution Overview

Problem

Existing headrest adjustment mechanisms in child safety seats are prone to failure during collisions, leading to loosening of the headrest and compromising safety due to displacement of the limiting member.

Innovation Solution

A headrest adjustment mechanism with an elastic device connecting the driving member and limiting member, featuring inclined surfaces and snap positions, ensures the headrest remains locked by transitioning from an unlocked to a locked state, preventing loosening during external collisions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a limiting member is used to lock the headrest at adjusted positions, then the headrest can be securely locked in place, but the limiting member may be displaced during a collision, causing the headrest to loosen and compromising safety

Engineering Contradiction:
Improvelocking reliabilityVSAvoidcollision impact
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The driving member is pre-configured with inclined surfaces that automatically engage with the limiting member when the headrest is pressed during a collision. This preliminary anti-action prevents the limiting member from being displaced backward, countering the harmful effect of collision forces before they can compromise the locking reliability

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The elastic device is pre-loaded to maintain continuous contact between the driving member and limiting member. This preliminary action ensures that the locking mechanism is always under light pressure, ready to resist collision forces and maintain locking reliability without requiring additional activation during a crash

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If the limiting member is allowed to move freely for adjustment, then the headrest can be easily repositioned, but the limiting member may unintentionally disengage during normal use

Engineering Contradiction:
Improveadjustment easeVSAvoidlocking stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The driving member acts as an intermediary between the limiting member and the headrest pressing force. It translates the pressing action into controlled movement of the limiting member along the inclined surfaces, enabling easy adjustment while preventing unintentional disengagement through the guiding inclined surfaces

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The mechanism transitions from a static locking position to a dynamic adjustment state when the headrest is pressed. The inclined surfaces guide the limiting member through a controlled movement path, allowing easy repositioning while maintaining reliability through the structured interaction between components

Inventive Principle:
Principle #15Dynamics

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 mechanism stabilizes the headrest position by engaging and disengaging the limiting member with snap positions, ensuring the headrest remains securely locked, enhancing safety and stability during normal use and crashes.

Implementation Method 1

an elastic device is connected between the driving member and the limiting member; and the elastic device is configured to make the limiting member tend to be locked in the snap position and to reset the driving member

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a first inclined surface is provided at the bottom of the snap block portion, and the first inclined surface is inclined from bottom to top in a direction close to the mounting bracket; and under the condition in which the headrest is pressed under an external force, the headrest drives the limiting member, and the first inclined surface abuts against the snap position, so as to move the snap block portion in a direction of disengagement from the snap position

Methodology Applied
Scientific EffectInclined plane: Inclined Plane

Data Source

PatentEP4389517B1Headrest adjustment mechanism and seat
Publication Date: 2026.02.18 NINGBO BABY FIRST BABY PROD CO LTD
  • EP4389517B1 patent drawingFigure 1~2
  • EP4389517B1 patent drawingFigure 3~4
  • EP4389517B1 patent drawingFigure 5~6

AI summary

The present invention relates to a headrest adjustment mechanism and a seat with such a mechanism. The headrest adjustment mechanism includes a headrest (200) movably connected to a mounting bracket (100) with a plurality of snap positions (101) disposed at intervals along a moving track and a driving member (300) in transmission connection with a limiting member (400) with a locking portion movably connected to the headrest, to enable the headrest adjustment mechanism to have a locked state and an unlocked state. In the locked state, the limiting member (400) is engaged with any one of the snap positions (101), and the locking portion is engaged with the driving member (300), so as to restrict a movement of the limiting member. In the unlocked state, the locking portion is disengaged from the driving member (300), and the driving member (300) drives the limiting member (400) to move to disengage the limiting member (400) from the snap position (101). In the locked state, the driving member can prevent the limiting member from loosening, thereby avoiding the loosening of the headrest due to an external collision, and improving the stability of the headrest.