Aircraft Seat Back Assembly With Controlled Forward Pivot
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Solution Overview
Problem
Existing seat back assemblies for vehicles, particularly aircraft, do not adequately address the need for enhanced robustness and safety during impact events, such as crash landings, to minimize injury to passengers.
Innovation Solution
A seat assembly design featuring a rotatable upper portion of the seat back that pivots forward under predetermined force, with a link mechanism and friction assembly to limit movement relative to the support frame, and a restoring mechanism to reset the seat back to its normal position, reducing deceleration and neck rotation during impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the seat back assembly is made rigid to withstand impact forces, then strength and reliability are improved, but the deceleration of the occupant's head during impact is increased, causing greater injury risk
Solution Approach 1:
The seat back assembly transitions from a static rigid structure to a dynamic system with controlled movement. The upper seat back fixing allows the seat back to pivot forward during impact, enabling the structure to adapt its configuration based on loading conditions. This dynamic behavior reduces head deceleration while maintaining overall structural strength.
Solution Approach 2:
The system changes the positional parameter of the seat back during impact events. By allowing the seat back to move from its normal upright position to a forward-pivoted position, the system modifies the kinematic parameters of the occupant restraint, thereby reducing harmful deceleration forces on the head.
2Object-affected harmful factors
If the seat back assembly is allowed to move freely during impact to reduce head deceleration, then injury risk is reduced, but the seat back becomes unstable during normal use
Solution Approach 1:
The connection system is divided into two distinct segments: the upper seat back fixing with rotatable connection that allows controlled movement during impact, and the lower seat back fixing with friction assembly that maintains stability during normal use. This segmentation enables different functional behaviors in different operational states.
Solution Approach 2:
The system transitions from a static stable configuration to a dynamic controlled-movement configuration during impact. The rotatable connection at the upper fixing enables the seat back to pivot forward, transforming the stable upright position into a dynamic impact-absorbing configuration that reduces head deceleration.
3Stability of the object's composition
If a friction assembly is used to limit seat back movement, then stability during normal use is maintained, but the device complexity increases
Solution Approach 1:
The friction assembly is designed to be self-regulating, using friction between the link and the friction assembly components to automatically limit movement without requiring external control systems. The spring element provides continuous contact force, and the system self-adjusts based on the applied loads, maintaining stability without complex control mechanisms.
4Object-affected harmful factors
If the link is configured to translate and rotate to increase horizontal distance, then the seat back can move forward during impact, but the manufacturing precision requirements increase
Solution Approach 1:
The link is designed as a dynamic component that undergoes both translation and rotation during impact. The sliding connection at the first end allows the link to move relative to the seat back, while the rotatable connection at the second end allows movement relative to the support frame. This dynamic configuration enables the horizontal distance to increase, facilitating seat back forward movement and reducing head deceleration.
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 design effectively reduces the likelihood and severity of injuries to passengers by absorbing impact forces and maintaining the seat back's stability, while allowing easy reset and compliance with safety standards.
Implementation Method 1
The friction assembly may apply an adjustable clamping force to the link
Implementation Method 2
The friction assembly may comprise Belleville washers. The Belleville washers may be mounted on a collar comprising a tubular portion which supports the washers and a flange which applies the clamping force to the link.
Implementation Method 3
The restoring mechanism may comprise a resilient element such as an elastomeric element or a spring.
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A seat assembly comprising a support frame, a seat back assembly, an upper seat back fixing and a lower seat back fixing, the upper seat back fixing and the lower seat back fixing configured to connect the seat back assembly to the support frame, wherein: the upper seat back fixing comprises a rotatable connection between the seat back assembly and the support frame; and the lower seat back fixing comprises a friction assembly configured to hold the seat back assembly in position relative to the support frame in normal use and configured to allow the seat back assembly to move relative to the support frame in response to greater than a predetermined force being applied to the seat back assembly.