Aircraft Seat Pan Clearance Zone for Lower Lumbar Load
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Solution Overview
Problem
The increased lumbar load experienced by aircraft seats during certification tests with the HIII-type dummy, due to the wider pelvis contacting the longitudinal members, exceeds the admissible load threshold, necessitating a redesign to accommodate the larger dummy size.
Innovation Solution
A seating surface structure with increased spacing between longitudinal members and the integration of a kinetic energy absorber tube to allow the pelvis to pass between them, reducing lumbar load by absorbing kinetic energy during impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the seating surface structure uses standard spacing between longitudinal members, then the structure maintains simplicity and structural integrity, but the wider pelvis of the HIII-type dummy contacts the longitudinal members causing excessive lumbar load
Solution Approach 1:
The patent applies local quality by creating a clearance zone with increased spacing between longitudinal members specifically in the pelvic region, while maintaining standard spacing in other areas. This localized modification allows the pelvis to pass through without contact, reducing lumbar load to below 1500 lbf, while preserving overall structural integrity and minimizing changes to the seating surface structure.
Solution Approach 2:
The seating surface structure is segmented into regions with different spacing characteristics: a clearance zone with increased spacing between longitudinal members in the pelvic region, and standard spacing in other regions. This segmentation allows the structure to simultaneously accommodate the wider pelvis of the HIII-type dummy while maintaining overall structural integrity.
2Strength
If the spacing between longitudinal members is increased to accommodate the wider pelvis, then lumbar load is reduced, but the structural integrity and stability of the seating surface may be compromised
Solution Approach 1:
The patent applies local quality by creating a clearance zone with increased spacing between longitudinal members specifically in the pelvic region, while maintaining standard spacing in other areas. This localized modification allows the pelvis to pass through without contact, reducing lumbar load to below 1500 lbf, while preserving overall structural integrity and minimizing changes to the seating surface structure.
3Adaptability or versatility
If the seating surface is designed for the HII-type dummy, then the lumbar load remains below the threshold, but the design does not accommodate the larger HIII-type dummy with wider pelvis
Solution Approach 1:
The patent applies parameter changes by modifying the spacing parameter between longitudinal members in the clearance zone. This parameter modification allows the seating surface to accommodate the larger dimensions of the HIII-type dummy, specifically the wider pelvis, while maintaining lumbar load below the 1500 lbf threshold through the reduced contact area.
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 modified seating surface design effectively reduces lumbar load below the threshold, validating certification with the HIII-type dummy by dissipating kinetic energy and diverting the pelvis trajectory.
Implementation Method 1
a kinetic energy absorber tube extending between the first longitudinal member and the second longitudinal member
Data Source
AI summary
The present invention relates to a seat pan having a seat pan structure that includes a first longitudinal member, a second longitudinal member, a front cross member and a rear cross member, wherein:each longitudinal member further includes a distal portion extending between the front end portion and the rear end portion;a gap between the first longitudinal member and the second longitudinal member measured between the distal portions is greater than a gap between the first longitudinal member and the second longitudinal member measured between the front end portions and/or a gap between the first longitudinal member and the second longitudinal member measured between the rear end portions.