Aircraft Seat Spring Actuator with Force Limiting

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Solution Overview

Problem

Aircraft seat adjustment mechanisms face challenges with complex mechanical power transmission, high friction, and design constraints due to the need for maximum adjustment force, which can be either fully active or fully inactive, lacking intermediate force control and comfort in movement.

Innovation Solution

Incorporating a spring element with a force-limiting mechanism that allows adjustable force application between seat elements, enabling comfortable movement by storing and releasing energy, and using a control unit to regulate force based on position, speed, and direction, potentially eliminating the need for separate mechanical or hydraulic systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If mechanical power transmission systems are used to transmit unlocking force from the control element to the locking element, then the adjustment mechanism can be actuated, but the device complexity increases and installation space is severely limited

Engineering Contradiction:
Improveadjustment mechanism actuationVSAvoidmechanical transmission complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent extracts the mechanical power transmission system from the adjustment mechanism, separating the control element from the locking element actuation. This allows the locking element to be actuated independently through a separate actuator, eliminating the need for complex cables, linkages, or hydraulic lines to transmit force across the aircraft seat structure.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a control unit as an intermediary between the control element and the actuator. The control unit receives signals from the control element and controls the actuator accordingly, providing a simple electronic mediation that replaces complex mechanical force transmission while maintaining the intended functionality.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Force

If mechanical power transmission systems with tight radii transitions are used, then force can be transmitted between seat elements, but the installation space is severely limited and design freedom is restricted

Engineering Contradiction:
Improveunlocking force transmissionVSAvoidinstallation space
Core Design Contradiction:
ForceVSArea of stationary object

Solution Approach 1:

The patent replaces the mechanical power transmission system with an electronic control system. Instead of transmitting mechanical force through cables and linkages with tight radii transitions, the system uses electrical signals to control an actuator, eliminating the need for complex mechanical pathways and freeing up installation space within the aircraft seat structure.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Force

If electrically driven adjustment mechanisms with actuators are used, then seat components can be adjusted against occupant weight, but the actuators become heavy and expensive

Engineering Contradiction:
Improveadjustment force against weightVSAvoidactuator weight
Core Design Contradiction:
ForceVSWeight of moving object

Solution Approach 1:

The patent applies partial action by using a spring element to provide only the necessary portion of adjustment force, rather than relying entirely on a heavy electric actuator. The spring element assists the actuator in moving seat components against occupant weight, allowing for a lighter actuator design while still achieving the required adjustment capability.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent uses a spring element as a counterweight mechanism to offset the weight of seat components and reduce the burden on the electric actuator. The spring element stores and releases mechanical energy to assist in moving the seat backrest and other components against gravitational force and occupant weight.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

4Productivity

If maximum adjustment force is always applied during movement, then adjustment can be achieved, but comfort during adjustment movement is reduced

Engineering Contradiction:
Improveadjustment capabilityVSAvoidadjustment comfort
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The patent implements dynamic force application through the spring element, which automatically adjusts the adjustment force based on the position and movement state of the seat components. The spring element provides variable assistance throughout the adjustment range, offering maximum force when needed and reducing force when approaching the target position, thereby improving comfort while maintaining productivity.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent incorporates feedback through the spring element's mechanical response to seat position changes. The spring element continuously adjusts its force output based on the current state of the adjustment mechanism, providing automatic force modulation that enhances comfort during adjustment movement while ensuring the adjustment capability is maintained.

Inventive Principle:
Principle #23Feedback

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 solution provides adjustable force levels for comfortable seat adjustments, preventing undesired movements and ensuring safety, while reducing design constraints and operational complexity, allowing for precise control of seat element interactions without the need for heavy servomotors.

Implementation Method 1

a spring element is provided which moves the second seat element relative to the first seat element

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP3297916B1Aircraft seat and method for adjusting an aircraft seat
Publication Date: 2022.08.24 LUFTHANSA TECHNIK AG
  • EP3297916B1 patent drawingFigure 1~2
  • EP3297916B1 patent drawingFigure 3
  • EP3297916B1 patent drawingFigure 4

AI summary

An aircraft seat (3) comprising – a first and a second seat element (1, 2), wherein – the second seat element (2) is mounted adjustably in relation to the first seat element (1), wherein – a spring element (4) moving the second seat element (2) in relation to the first seat element (1) is provided, wherein – the force acting on the second seat element (2) by means of the spring element (4) can be released by means of an actuator (5), and therefore, in a first switching position of the actuator (5), the spring element (4) is deactivated, and, in a second switching position of the actuator (5), the spring element (4) is activated, wherein – a force-limiting element (6) is provided with which the force acting on the second seat element (2) by means of the spring element (4) can be limited to a predefined value, and therefore intermediate states between the first and the second switching position can also be set.