Chairs including flexible frames
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Solution Overview
Problem
Existing chair designs lack flexibility to adjust pressure and movement while maintaining sufficient strength, leading to discomfort and uncertainty about reaching maximum safe deflection, as they often exhibit uniform stiffness without clear indication of impending failure.
Innovation Solution
The chair features back and seat supports designed with multiple bending stiffness levels, utilizing bars and stop devices to limit movement at specific points, allowing for initial flexibility and subsequent increased stiffness to ensure safe support and indicate maximum deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the back support is designed with uniform stiffness, then the structure is simple and strong, but the occupant experiences discomfort and has no indication of maximum safe deflection
Solution Approach 1:
The back support transitions from a static uniform stiffness structure to a dynamic system with variable stiffness. The mechanism allows the back support to change its bending characteristics based on the degree of deflection, providing initial flexibility for comfort and then increasing stiffness to indicate maximum safe deflection through tactile feedback and visual indicators.
Solution Approach 2:
The back support is divided into multiple functional segments with different stiffness characteristics. The first portion provides initial flexibility with lower stiffness, while the second portion provides structural support with higher stiffness. This segmentation allows each portion to serve its specific function optimally.
2Ease of operation
If the back support is made very flexible to allow movement and pressure relief, then comfort is improved, but the strength to safely support an occupant is reduced
Solution Approach 1:
The back support employs a dynamic stiffness mechanism where the effective stiffness changes with the degree of deflection. During normal use with small deflections, the support feels flexible and comfortable. As deflection approaches the maximum safe limit, the stiffness increases dramatically, providing both enhanced support strength and tactile feedback to the occupant.
Solution Approach 2:
Different portions of the back support have different local stiffness properties. The first portion near the occupant contact area is designed to be more flexible for comfort, while the second portion providing structural support is designed to be stiffer. This local differentiation allows the structure to be both comfortable and strong.
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 design provides comfortable movement and pressure relief by varying stiffness based on deflection, ensuring safe support and clear indication of maximum safe deflection, enhancing user experience during posture changes and office tasks.
Implementation Method 1
each back support is configured to exhibit a first bending stiffness when bent to a first stop point, and exhibit a second bending stiffness when bent beyond the first stop point
Data Source
AI summary
A chair includes a base and a back coupled to the base. The back includes a pair of back supports extending from the base and a back panel coupled to the pair of back supports. Each back support is configured to exhibit a first bending stiffness when bent to a first stop point, and exhibit a second bending stiffness when bent beyond the first stop point, the second bending stiffness being greater than the first bending stiffness.