Airplane Seat Force-Limiting Mechanism for Crash Safety
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Solution Overview
Problem
Aircraft seats face challenges in managing occupant loads during crashes, as existing designs either result in excessive displacement leading to collisions or require excessive space, compromising comfort and safety, and existing force-limiting devices do not effectively distribute energy dissipation without structural damage.
Innovation Solution
The aircraft seat incorporates a dual-force limiting system with adjustable securing devices that allow precise activation of force-limiting mechanisms, preventing premature loading and ensuring defined force distribution, enabling controlled relative movement between the seat base and surface assembly, thereby optimizing occupant safety and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the seat substructure rigidity is designed to limit forces on the passenger through deformation, then occupant safety is improved, but excessive translational displacement occurs leading to collisions with fixed parts
Solution Approach 1:
The seat assembly is divided into functionally independent components: the seat substructure for structural support, and a separate force-limiting device for energy absorption. This segmentation allows the force-limiting device to handle crash forces through controlled deformation while the seat substructure maintains its rigidity, preventing excessive displacement and collisions.
Solution Approach 2:
The force-limiting device acts as an intermediary element between the seat substructure and the seat surface assembly. It absorbs crash forces through its own controlled deformation, protecting the passenger from both excessive forces and excessive displacement, while preventing direct load transfer to the seat substructure.
2Volume of stationary object
If the movement envelope is kept small to prevent collisions, then space efficiency is improved, but the distance covered by the head in a crash becomes too short leading to injury
Solution Approach 1:
The force-limiting device serves as an intermediary that enables a larger movement envelope while protecting the occupant. It allows the seat surface assembly to move a safe distance during crash without requiring excessive space, as the force-limiting device absorbs energy through controlled deformation over an extended distance.
Solution Approach 2:
The force-limiting device changes the force parameters during crash by providing progressive resistance through deformation. This allows the system to convert high-impact forces into controlled, lower-magnitude forces over a longer distance, enabling safer occupant movement within limited space.
3Reliability
If a force-limiting device is introduced to dissipate kinetic energy, then occupant safety is improved, but the device complexity increases
Solution Approach 1:
The force-limiting function is extracted as a separate, dedicated device rather than being integrated into the seat substructure. This allows the force-limiting device to be optimized for energy absorption while the seat substructure remains simple and focused on structural support, overall reducing system complexity.
Solution Approach 2:
The force-limiting device is designed as a sacrificial component that deforms and absorbs energy during crash, then can be replaced or reset. This allows the main seat structure to remain intact and reusable, reducing the need for complex safety systems throughout the entire assembly.
4Reliability
If the first securing device has a higher deformation limit to protect the first force-limiting device, then the force-limiting device reliability is improved, but the device complexity increases
Solution Approach 1:
The first securing device with higher deformation limit acts as a protective cushion for the first force-limiting device during normal operation. It absorbs minor shocks and vibrations before they reach the force-limiting device, protecting it from premature activation or damage without requiring complex protection mechanisms.
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 enhances crash safety by precisely managing occupant stress, preventing injuries, and allowing for a lightweight, structurally sound seat design with improved comfort and space efficiency by distributing kinetic energy effectively without structural deformation.
Implementation Method 1
the first securing device having a higher deformation limit when the seat surface assembly moves in relation to the seat base or vice versa in the direction of the first relative movement has the force limitation level required to activate the first force limitation device
Implementation Method 2
The force limiting device between the seat base and the seat surface assembly enables the kinetic energy of a passenger on the seat to be dissipated in the event of a crash
Data Source
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AI summary
The invention relates to an airplane seat (1) with a seat assembly (3). The seat assembly (3) comprises a seat base (5) and a seat surface assembly (4). A first force limiting device (9) is provided between the seat base (5) and the seat surface assembly (4), said force limiting device allowing a first relative movement between the seat base (5) and the seat surface assembly (4) upon being activated. The seat surface assembly (4) is supported against the seat base (5) in the direction of the first relative movement via a first securing device (18), and the first securing device (18) has a higher deformation limit than the force limit level required to activate the first force limiting device (9) when the seat surface assembly (4) is moved relative to the seat base (5) or vice versa in the direction of the first relative movement.