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 to safely support occupants, often leading to discomfort and uncertainty about reaching maximum safe deflection.
Innovation Solution
The chair features back and seat supports with distinct bending stiffness levels, transitioning from a first stiffness to a higher second stiffness at specific stop points, achieved through the use of bars and stop devices that limit movement, allowing for comfortable movement and increased support as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the back support is made flexible to allow movement and decrease pressure, then comfort and ease of operation are improved, but the strength and reliability deteriorate because the support may not be strong enough to safely support an occupant
Solution Approach 1:
The back support transitions from a static structure to a dynamic one with variable stiffness. The support exhibits a first bending stiffness when bent to a stop point, allowing flexible movement for comfort, and a second bending stiffness greater than the first when bent beyond the stop point, providing enhanced strength for safety. This dynamic adjustment of mechanical properties resolves the contradiction between flexibility and strength.
2Ease of operation
If the seat support is made flexible to alleviate pressure under knees, then comfort is improved, but the overall pressure increases and the support strength decreases
Solution Approach 1:
The seat support applies local quality by providing different stiffness characteristics at different locations and conditions. The support exhibits a first bending stiffness that allows localized flexing to relieve pressure under the knees, improving comfort. When bent beyond the stop point, it transitions to a second bending stiffness greater than the first, redistributing the load and reducing overall pressure while maintaining adequate support strength.
3Ease of manufacture
If the back support exhibits uniform stiffness, then manufacturing is simplified, but the occupant cannot detect when maximum safe deflection is reached, reducing reliability
Solution Approach 1:
The back support incorporates feedback through its variable stiffness characteristic. When bent to the stop point, the transition from first bending stiffness to second bending stiffness (greater than the first) provides tactile feedback to the occupant, indicating that maximum safe deflection has been reached. This feedback mechanism enhances reliability without significantly complicating manufacturing, as it utilizes the inherent mechanical properties of the support structure.
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 a comfortable, flexible, and safe seating experience by allowing initial low stiffness for movement and increasing stiffness significantly at defined stop points, indicating maximum safe deflection and ensuring occupant support.
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.