Tread-Overhang Folding Stair for Collision-Free Stowage
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Solution Overview
Problem
Folding stairs with short tread depths are difficult to traverse due to potential collisions between steps during the folding process, which is a common issue in existing folding stair designs.
Innovation Solution
Incorporating tread overhang and utilizing rotating axes with specific inclination and azimuth offsets, along with fold-coordinating mechanisms, allows the steps to rotate beyond the critical angle of collision without overlapping, ensuring safe and efficient folding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the tread depth is extended beyond the run length to improve safety and comfort, then the step area is increased, but the steps collide during folding motion
Solution Approach 1:
The patent applies dimensionality change by offsetting the rotation axis from the traditional position (at the edge of the step run) to a position beyond the end of the run. This spatial repositioning in another dimension allows the tread to overhang the run length without interfering with the folding path of adjacent steps, resolving the collision problem while maintaining increased tread area for safety and comfort
2Device complexity
If the tread depth is shortened to enable compact folding, then the folding angle is increased, but the traversal difficulty increases
Solution Approach 1:
By repositioning the rotation axis beyond the run length in a different spatial dimension, the patent enables the tread to extend further without increasing the horizontal footprint during folding. This allows the stair to achieve compact folding while maintaining adequate tread depth for easy traversal, as the overhanging portion does not obstruct the folding motion of adjacent steps
3Device complexity
If the rotation axis is positioned at the traditional location, then the structure is simple, but the tread depth cannot exceed the run length
Solution Approach 1:
The patent maintains structural simplicity by using a basic rotation axis mechanism, but relocates it to a position beyond the end of the run length. This dimensional repositioning allows the tread to naturally overhang the run without requiring complex additional structures, achieving increased tread area while keeping the overall design simple and elegant
Data Source
AI summary
An improved folding stair comprising a sequence of steps (101), each rotably mounted to a structure (102) via axes (103) located and oriented to facilitate rotation between deployed and stowed states, such that the steps exhibit tread overhang (109) in their deployed state. The step width (105) exceeds the step rise (107). In other embodiments the axes are to one side of the steps. In other embodiments the angle of rotation between deployed and stowed states exceeds the arccosine of step-above thickness (104) over step rise. In other embodiments the movement from deployed to stowed state moves the steps from the traversal path. In other embodiments the axes are either skew to the deployed tread, or to the traversal path, or to both. Other embodiments include a means of coordinating the steps' folding motion.