Actuatorless Seat Armrest Deployment Through Dual-Roller Guides

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Solution Overview

Problem

Existing aircraft seat armrests are not synchronized with the seat's movement, leading to inconsistent performance across different seat models due to varying backrest kinematics, necessitating separate actuators for armrest positioning.

Innovation Solution

A seat mechanism with a movable armrest that automatically adjusts between high and low positions via a deployment mechanism, utilizing guide linkages and tilting rods integrated with the seat's movement, eliminating the need for separate actuators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the armrest is mechanically connected to the backrest via a deployment mechanism, then the armrest can move between raised and lowered positions, but the armrest movement becomes dependent on backrest kinematics which vary between seat models

Engineering Contradiction:
Improvearmrest positioningVSAvoidcompatibility across seat models
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

A guide linkage mechanism is introduced as an intermediary between the seat and armrest. This guide linkage includes a guide member fixed to the seat and a follower member on the armrest that engages with the guide member, thereby mediating the movement between seat position and armrest position while being independent of backrest kinematics

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The deployment mechanism is segmented into independent components: a guide linkage system separate from the backrest mechanism, with the guide member fixed to the seat structure and the follower member independently engaged with the armrest. This segmentation allows the armrest positioning system to function independently of backrest variations

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If a separate actuator is added to control armrest movement, then armrest positioning is improved, but device complexity and mechanical stress on the seat increase

Engineering Contradiction:
Improvearmrest positioningVSAvoidactuator system
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The armrest positioning system is designed to be self-servicing through passive mechanical linkage. The guide linkage automatically responds to seat position changes without requiring external power or control systems. The follower member passively follows the guide member's movement, eliminating the need for motors, sensors, or control electronics

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The guide linkage acts as a mechanical intermediary that translates seat movement into armrest positioning without requiring active actuators. This passive mediation reduces device complexity by replacing powered actuation systems with simple mechanical guidance

Inventive Principle:
Principle #24Intermediary (Mediator)

3Stability of the object's composition

If the armrest is fixed to the seat structure, then structural stability is maintained, but the armrest cannot adjust position with seat movement

Engineering Contradiction:
Improvearmrest structural stabilityVSAvoidarmrest position adjustment
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The armrest connection is transformed from a static fixed attachment to a dynamic adjustable linkage. The guide linkage allows the armrest to change position relative to the seat while maintaining structural integrity through the engaged guide member and follower member connection

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4405252B1Actuatorless movable seat armrest
Publication Date: 2025.11.05 SAFRAN SEATS
  • EP4405252B1 patent drawingFigure 1~2a
  • EP4405252B1 patent drawingFigure 2b~2c
  • EP4405252B1 patent drawingFigure 3~4

AI summary

The invention relates to a seat that can be converted between an upright position and a bed position, comprising a mechanism (23) for deploying an armrest (17), which mechanism comprises: - a first guide connection (35) comprising a first roller (36) mechanically connected to the moving part (37) associated with the seat-cushion portion, the first roller (36) collaborating with a first slot formed in the armrest (17), and - a second guide connection (40) comprising a second roller (41) mechanically connected to a fixed part (26), the second roller (41) collaborating with a second slot formed in the armrest (17) such that a movement of the seat-cushion portion of the seat as the seat transitions from the upright position to the bed position causes the armrest (17) to move from the up position to the down position.