Convertible Seat Assembly With Locking Pivot for Casualty Evacuation

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Solution Overview

Problem

Existing seat assemblies in vehicles, particularly military vehicles, do not allow for safe removal and transportation of an occupant to a safe location, such as a hospital, following a violent external event or accident, without first removing the person from the seat.

Innovation Solution

A removable and mountable seat assembly with a pivotally connected seat back and seat pan that can rotate relative to each other, featuring a locking device to convert between a seated position and a flat stretcher configuration, and includes safety restraints and energy attenuating capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the seat assembly is fixed into place to provide stability and safety during normal operation, then the reliability is improved, but the adaptability deteriorates because the seat cannot be converted into a stretcher for emergency evacuation

Engineering Contradiction:
Improvestability of seat assemblyVSAvoidconvertibility to stretcher
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The seat assembly incorporates a rotatable seat back connected to the seat pan through a pivot axis, allowing the configuration to dynamically change between a fixed seated position and a flat stretcher position. This dynamic mechanism enables the seat to adapt its structure in response to different operational requirements, resolving the contradiction between fixed stability and convertible versatility.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The seat assembly is designed to perform multiple functions: it serves as a regular seat during normal vehicle operation and can be converted into a stretcher for emergency evacuation or medical transport. The locking device and rotatable connection enable a single structure to fulfill both seating and stretcher functions, eliminating the need for separate fixed seat and stretcher systems.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Strength

If the seat assembly is made fixed and rigid to provide structural strength, then the strength is improved, but the ease of operation deteriorates because the seat cannot be easily converted or removed

Engineering Contradiction:
Improvestructural strength of seatVSAvoidease of conversion to stretcher
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The seat back is connected to the seat pan through a rotatable joint with a defined axis of rotation, allowing the rigid structural components to move relative to each other. This dynamic connection maintains structural integrity when locked in seat position while enabling easy conversion to stretcher position through rotation, resolving the contradiction between structural strength and operational ease.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The seat assembly is divided into distinct segments (seat pan, seat back, locking device) that can move independently relative to each other. The seat back can rotate about the pivot axis while remaining structurally sound, and the locking device can engage or disengage to fix or release the configuration, making the strong structure easy to operate.

Inventive Principle:
Principle #1Segmentation

3Stability of the object's composition

If the seat back and seat pan are rigidly connected to maintain fixed position, then the stability is improved, but the adaptability deteriorates because the seat cannot assume multiple configurations

Engineering Contradiction:
Improvefixed position of seat componentsVSAvoidmultiple configurations
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The rotatable connection between seat back and seat pan creates a dynamic system that can maintain stable fixed positions (locked seat configuration or locked stretcher configuration) while also being capable of transitioning between these positions. The locking device ensures stability in each configuration while the rotatable mechanism enables adaptability between configurations.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3941411B1Removable and convertible seat assembly
Publication Date: 2026.03.04 PRATT & MILLER ENG & FABRICATION LLC
  • EP3941411B1 patent drawingFigure 1
  • EP3941411B1 patent drawingFigure 2A~2B
  • EP3941411B1 patent drawingFigure 2C~2D

AI summary

A removable and/or mountable seat assembly includes a seat back and a seat pan that are pivotally connected to each other via a locking device and rotate about at least one common axis of rotation. The locking device is in mechanical communication with the seat back and the seat pan and is configured to lock the seat back and the seat pan relative to each other about the at least one common axis of rotation. The locking device is configured to selectively lock the seat pan and the seat back such that the seat back and the seat pan lie along the common plane forming the stretcher or selectively lock the seat pan and the seat back such that the seat back and the seat pan form a seat. Additionally, the seat back and the seat pan may be locked in yet another position allowing for the easy transport and/or storage of the seat assembly.