Expandable Seat Leg Joint for Crash Load Absorption
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Solution Overview
Problem
Passenger seats in vehicles face separation from the cabin floor during crashes, leading to reduced survivability and non-compliance with regulatory requirements due to rigid mounting, which does not allow for deformation of the cabin floor or support structures.
Innovation Solution
An extendable joint is introduced between the passenger seat frame and the cabin floor or support structure, preloaded to prevent motion under normal conditions but allowing relative motion and force absorption during emergencies, reducing the likelihood of seat separation by distributing forces over a longer period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If rigid mounting is used to improve passenger confidence and comfort, then passenger confidence and comfort are improved, but separation occurs during cabin floor deformation leading to reduced survivability
Solution Approach 1:
The seat mounting system transitions from a static rigid connection to a dynamic extendable joint that adapts its characteristics based on loading conditions. Under normal conditions, the joint maintains a rigid locked state for passenger comfort, while under crash conditions it extends to accommodate floor deformation, preventing seat separation and maintaining attachment reliability.
Solution Approach 2:
The extendable joint changes its structural parameters (length, stiffness) in response to applied forces. The joint extends from its retracted position during crash deformation, changing the geometric parameters of the mounting system to accommodate cabin floor movement while maintaining secure attachment.
2Device complexity
If rigid mounting is used to simplify the structure, then device complexity is reduced, but the seat fails to accommodate cabin floor deformation during crashes
Solution Approach 1:
The mounting system is divided into separate components: a fixed mounting base, an extendable joint mechanism, and a seat leg. This segmentation allows the extendable joint to specifically handle deformation accommodation while other components maintain their functions, achieving adaptability without requiring complete redesign of the entire mounting system.
Solution Approach 2:
The extendable joint acts as an intermediary element between the fixed cabin floor mounting points and the seat structure. This intermediate component absorbs the deformation compatibility issue by extending and contracting, allowing the rigid seat and rigid floor to work together despite their incompatibility during crash events.
3Reliability
If extendable joint is introduced to allow motion during crash, then survivability is improved, but additional components increase device complexity
Solution Approach 1:
The extendable joint uses a dynamic locking mechanism that automatically transitions between locked and extended states based on applied forces. This self-actuating dynamic behavior reduces the need for additional control systems, sensors, or actuators, maintaining relatively simple device complexity while achieving improved crash reliability.
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 extendable joint effectively reduces the loading on seat attachment points, preventing separation and enhancing survivability by distributing crash forces, thus meeting regulatory standards such as the 16G Pitch and Roll Test.
Implementation Method 1
a preload mechanism for stabilizing the extendable joint up to a threshold force so as to allow relative motion between the front seat leg and the extension fixture beyond the threshold force
Implementation Method 2
The preload mechanism is tuned so as to prevent relative motion between the front seat leg and the extension fixture along the first slot and second slot below a threshold force
Implementation Method 3
The extension of the passenger seat frame or leg absorbs and distributes the forces applied to the passenger seat over a longer period of time and a greater range of motion
Implementation Method 4
The extension of the passenger seat frame or leg absorbs and distributes the forces applied to the passenger seat over a longer period of time and a greater range of motion. The result is decreased loading of the seat to floor attachment points
Implementation Method 5
the front seat leg comprising a first slot and a first clearance recess and the extension fixture comprising a second slot and a second clearance recess to allow for a greater overlap of the front seat leg and extension fixture
Data Source
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AI summary
Described is an extendable joint (10,100) for attaching a passenger seat to a cabin floor or support structure. The extendable joint (10,100) exhibits behavior of a rigid mounting during normal usage, such as when carrying or securing passengers or luggage. However, if a force threshold is exceeded, such as with an emergency situation, the extendable joint (10,100) may lengthen to absorb energy applied from the cabin floor through the passenger seat and vice versa. Additional force damping mechanisms may also be incorporated into the joint to further absorb, distribute, or reduce loadings that may otherwise separate the passenger seat from the floor or support structure.