Seat Back Fixing With Friction Release for Head Impact Protection
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Solution Overview
Problem
Existing seat back assemblies for vehicles, particularly aircraft, do not adequately address the need for enhanced safety and robustness to minimize injury during head impact events by absorbing vibration, shock loads, and extreme conditions, while ensuring compliance with safety standards.
Innovation Solution
A seat assembly with a rotatable upper seat back fixing and a friction assembly in the lower fixing that allows the seat back to move relative to the support frame under a predetermined force, featuring a link mechanism to limit excessive movement and a restoring mechanism to reset the seat back to its normal position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the seat back assembly is made rigid and firmly fixed to the support frame, then the structural strength and stability are improved, but the ability to reduce head deceleration and minimize injury during impact events deteriorates
Solution Approach 1:
The seat back assembly incorporates a rotatable connection at the upper fixing point, allowing the seat back to dynamically rotate forward during impact events. This dynamic movement transforms the rigid structure into a compliant system that can absorb impact energy while maintaining structural integrity, thereby reducing head deceleration without compromising strength
Solution Approach 2:
The friction assembly is designed to change its friction parameter based on applied force - maintaining high friction (locked state) during normal use for stability, but allowing the seat back to move when a predetermined force threshold is exceeded during impact. This parameter change enables the system to provide both strength and impact protection
2Object-affected harmful factors
If the seat back assembly is made compliant and movable to reduce impact forces, then the ability to minimize head deceleration is improved, but the structural stability and position holding capability deteriorates
Solution Approach 1:
The system transitions from a static fixed connection to a dynamic friction-based connection that adapts its characteristics based on operating conditions. During normal use, the friction assembly maintains stable positioning; during impact, it allows controlled movement to reduce head deceleration
Solution Approach 2:
The friction assembly changes its friction parameter from high (locked) during normal use to low (slipping) during impact events. This parameter change is triggered by the magnitude of applied force, enabling the system to maintain stability when needed and provide compliance during impact
3Object-affected harmful factors
If a friction assembly is used to allow controlled movement during impact, then the ability to reduce neck rotation is improved, but the device complexity increases
Solution Approach 1:
The friction assembly is extracted as a separate, modular component that can be independently designed and adjusted. This extraction allows the complex friction control function to be isolated from the main structural elements, simplifying the overall system integration while maintaining the neck rotation reduction capability
Solution Approach 2:
The friction assembly acts as an intermediary element between the rigid support frame and the seat back assembly. It mediates the interaction between these two components, providing controlled movement during impact while maintaining structural connection, thereby reducing neck rotation without requiring complex direct coupling 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
Reduces head deceleration and neck rotation during a head impact event, minimizing injury to both the passenger and the one behind, while maintaining compliance with safety standards and allowing easy resetting after unintended activation.
Implementation Method 1
The friction assembly is configured to prevent movement of the seat back assembly relative to the support frame in normal use
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.
Data Source
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.