Foldable Stretcher Wire Tensioning and Segmentation
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Solution Overview
Problem
Existing foldable stretchers either fail to reduce width adequately or become too cumbersome when attempting to balance lightness and stability, making them difficult to carry and store efficiently.
Innovation Solution
A foldable stretcher design featuring pivotally connected plane members, props, and stiff wires that can be tautened to fixate the structure in an unfolded position, allowing for compact folding and easy transportation, while maintaining stability and lightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If multiple fold lines are used to reduce width, then the stretcher becomes more compact for transport, but the structure becomes more complex and heavier
Solution Approach 1:
The stretcher is divided into multiple plane members (head piece, body pieces, foot piece) that can be folded relative to each other. Each plane member is a separate segment that pivots on hinges, allowing the entire structure to collapse into a compact configuration while maintaining structural integrity through the hinge connections.
Solution Approach 2:
The stretcher utilizes multi-dimensional folding by allowing plane members to rotate about hinge axes that are perpendicular to the longitudinal axis. This creates a compact three-dimensional folded configuration rather than simply bending along one dimension, significantly reducing the overall volume while using fewer fold lines.
2Weight of moving object
If the stretcher is made lightweight for easy carrying, then portability improves, but structural strength and stability deteriorate
Solution Approach 1:
The plane members are constructed from composite materials such as aluminum alloy profiles or composite beams that combine lightweight properties with high strength-to-weight ratio. These composite structures provide the necessary structural strength while maintaining minimal weight for easy carrying by emergency personnel.
Solution Approach 2:
The stretcher employs different material properties at different locations: heavier reinforcement is placed at critical load-bearing points such as hinge connections and support props, while other areas use lighter materials. This localized quality optimization ensures strength where needed without unnecessarily increasing overall weight.
3Volume of moving object
If the stretcher is designed to be compact for storage and transport, then ease of storage improves, but ease of deployment deteriorates
Solution Approach 1:
The stretcher features dynamic hinge connections that allow smooth, controlled unfolding motion. The hinges are designed with appropriate clearance and lubrication to enable easy deployment from the compact folded state to the full operational configuration, making rapid deployment intuitive and straightforward for emergency personnel.
Solution Approach 2:
The stretcher is pre-assembled with all components (plane members, hinges, props, wires) already connected and configured in the folded state. This preliminary assembly eliminates the need for on-site construction or complex assembly procedures, allowing emergency personnel to simply unfold and deploy the stretcher quickly without tools or additional steps.
4Stability of the object's composition
If props are added to support the stretcher in unfolded position, then stability improves, but device complexity and weight increase
Solution Approach 1:
The props are designed to be self-positioning support elements that automatically engage with the plane members when the stretcher is unfolded. The props utilize the inherent geometry and gravity to self-align and support the stretcher structure without requiring additional actuators, control systems, or complex mounting mechanisms, thereby maintaining simplicity while providing stable support.
Data Source
AI summary
A foldable stretcher for transporting an object. The stretcher comprising: a plurality of substantially plane members pivotally connected with each other in series by means of hinges there between; handles pivotally connected to outermost of the plane members; and, at least two pluralities of props. The stretcher further comprises at least two pairs of sufficiently stiff wires. Each pair of the wires arranged along a corresponding long side of the stretcher; each the wire is mechanically connected to the stretcher at least two connection points; the handles adapted for actuating a tautening of at least one of the wires of each pair of wires by fixation of the handles when the stretcher is in the unfolded position.