S-Shaped Leaf Spring Chair with Adjustable Swivel Firmness
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Solution Overview
Problem
Existing chairs with synchronous seat and backrest mechanisms lack sufficient adjustability in swivel movement, particularly in adapting to different user weights and providing three-dimensional dynamic seating.
Innovation Solution
A chair design featuring an S-shaped leaf spring with a compressible spacer displaceably guided along its first section, allowing adjustment of the effective lever arm and firmness of the leaning-back movement, facilitated by an actuating element that rotates to change the spacer's position, and optionally using a steel spring with a progressive spring characteristic curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a synchronous mechanism with fixed ratio is used to couple the seat and backrest, then the seat and backrest move together in a coordinated manner, but the adjustability of the swivel movement is insufficient
Solution Approach 1:
The patent applies the dynamics principle by making the coupling between seat and backrest adjustable rather than fixed. The synchronous mechanism allows variable movement ratios through adjustable linkages, enabling the system to adapt to different user preferences and weights while maintaining coordinated movement. This transforms a static, fixed-ratio mechanism into a dynamic, adjustable one that can change its characteristics during operation.
Solution Approach 2:
The patent implements parameter changes by allowing key geometric parameters of the synchronous mechanism to be adjusted. Specifically, the positions of pivots, linkages, and spring elements can be modified to change the movement ratio between seat and backrest. This enables customization of the swivel movement characteristics without fundamentally changing the mechanism's structure, resolving the contradiction between adaptability and complexity.
2Adaptability or versatility
If separate spring elements are used for the seat and backrest support, then the swivel movement can be cushioned, but the firmness cannot be adapted to different user weights
Solution Approach 1:
The patent applies universality by designing a combined spring element that serves multiple functions: it cushions the swivel movement, supports both the seat and backrest, and can be adjusted to accommodate different user weights. The single S-shaped spring element with adjustable characteristics replaces multiple fixed spring elements, allowing the same component to adapt to various loading conditions while maintaining its cushioning function.
Solution Approach 2:
The spring element's characteristics are made dynamic and adjustable rather than fixed. The firmness of the spring can be modified to match different user weights, transforming a static spring system into an adaptive one. This allows the cushioning force to be optimized for each user while maintaining the same physical component, resolving the contradiction between adaptability and force characteristics.
3Adaptability or versatility
If multiple S-shaped leaf springs are used to provide stable swivel movement, then the chair allows three-dimensional dynamic seating, but the number of components increases
Solution Approach 1:
The patent applies merging by combining multiple spring elements into a single integrated S-shaped leaf spring. This unified structure provides the necessary support and cushioning for three-dimensional dynamic seating while reducing the total number of components. The combined spring element incorporates the functionality of what would otherwise require separate springs, simplifying the overall construction while maintaining the desired mechanical behavior.
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
Enables adjustable and intuitive adjustment of the swivel movement to accommodate various user weights, allowing both backward and lateral tilting, enhancing user comfort and reducing environmental impact through the use of steel and plywood materials.
Implementation Method 1
A compressible spacer (6) that is displaceably guided in the longitudinal direction of the first section (4a) is provided between the first and the second section (4b)
Implementation Method 2
at least one S-shaped leaf spring (4), the S-shaped leaf spring (4) at a first section (4a) being fastened to the support frame (3)
Data Source
AI summary
The chair according to the invention has a seat, a backrest, a support frame, and at least one S-shaped leaf spring. The S-shaped leaf spring at a first section is fastened to the support frame, the seat is mounted at a second section, and the backrest is mounted at a third section. A first curvature is provided between the first and second sections, so that in a neutral position of the chair the first section and the second section are situated essentially in parallel to one another and are spaced apart, and the third section adjoins the second section via a second, opposite curvature. A compressible spacer that is displaceably guided in the longitudinal direction of the first section is provided between the first and the second section.