Folding Stair Four-Bar Linkage Flap Design
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Solution Overview
Problem
Existing folding stairs with hinged mechanisms require reinforced flaps to support loads, making them heavier and more complex, which complicates installation and transportation.
Innovation Solution
The design features a lightweight wooden stair system where the first stair section is connected to the frame with hinges, and a flap is suspended by connecting rods forming a four-bar linkage, with hook-type holders and tension springs to manage the opening and closing mechanism, allowing the flap to be lighter and easier to install, and reducing overall dimensions when folded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the flap is used as a supporting structure to withstand loads from stair sections and users, then the structural strength is improved, but the weight of the flap increases and the overall device becomes more complex
Solution Approach 1:
The patent extracts the supporting function from the flap and transfers it to the stair sections themselves. The stair sections are designed with integrated support capabilities, while the flap is reduced to a simple closing element that does not bear structural loads. This separation allows the flap to be lightweight and simple while the stair sections provide the necessary strength.
Solution Approach 2:
Instead of using the flap to support the stairs (conventional approach), the patent inverts the relationship by having the stairs support themselves and the flap merely close the opening. The stair sections are designed to bear their own weight and user loads, while the flap serves only as a closure panel.
2Strength
If the flap is reinforced to support loads, then the structural strength is improved, but the device complexity and installation difficulty increase
Solution Approach 1:
The supporting function is extracted from the flap and assigned to the stair sections. The flap becomes a simple non-structural closing element, eliminating the need for reinforcement and complex mounting structures. This simplifies both the design and installation processes.
3Strength
If the flap is reinforced to support loads, then the structural strength is improved, but the transportation and installation become more difficult
Solution Approach 1:
By extracting the load-bearing function from the flap and assigning it to the stair sections, the flap becomes a lightweight, easy-to-install closing panel. The stair sections are designed to be self-supporting, which simplifies the overall installation process while maintaining structural integrity.
4Strength
If the connecting mechanism uses traditional hinged flaps, then the structural strength is improved, but the clearance for user feet is reduced
Solution Approach 1:
The patent inverts the traditional mechanism by having the stair sections open away from the wall rather than having a flap close against it. This allows sufficient clearance for user feet during the opening and closing operation, while the stair sections themselves provide the necessary structural support.
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
This solution results in a more convenient and lightweight folding stair system that is easier to install and transport, with improved clearance for users and reduced dimensions when folded, facilitating easier access to loft and attic spaces.
Implementation Method 1
The insert which closes the mounting access to the hook-type holder seat is movably connected with the body of this hook-type holder through the elastic connecting member
Implementation Method 2
The latch also has an elastic connecting member which forms a movable connection between the catch and the insert
Implementation Method 3
The flap is suspended from the first section of stairs section by at least two pairs of connecting rods which, together with this first section of stairs and the flap itself, form a four-bar linkage
Implementation Method 4
The first stair section is connected in a pivoting manner with the frame by means of hinge holders fastened to inner wall of frame; and during unfolding of the stairs the axis of rotation of first stair section retains its position with respect to the frame
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Folding stairs have three sections of ladder-type stairs connected by hinges. The first section (11) of stairs is connected by a pivoting joint with the frame (2) by means of hinged holders (3) fitted from inside to the frame wall and during unfolding of these stairs the rotation axis of the first section (11) of stairs does not change its position with respect to the frame (2). The flap (4) is suspended from the first section (11) of stairs by means of at least two pairs of connecting members (41, 42), which together with the first section of stairs and the flap form a four-bar linkage. Each connecting member on which the flap is suspended is connected with the flap by means of a hook-type holder (5) having the bearing seat for the pin seated in the connecting member (41, 42).