Segmented Backrest Tilt Joint to Prevent Chair Pinching
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Solution Overview
Problem
Existing chair designs with tiltable backrests using elastic devices risk pinching the user due to large empty spaces between supports and require aesthetically undesirable bellows-shaped elements for safety, which are not fully effective.
Innovation Solution
The chair features elastic devices with multiple sectors and slits between them, where the elastic element has a central stretch and elongated flat springs fixed to top and bottom supports, distributing the bending across multiple sectors to prevent pinching and enhance comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a large empty space is provided between the supports of each elastic element to enable backwards tilting movement with desired amplitude, then the tilting range is improved, but the risk of pinching the user increases
Solution Approach 1:
The elastic device is divided into multiple sectors (first sector, second sector, third sector) stacked on top of one another. Each sector contains a portion of the elastic element, and slits are formed between adjacent sectors. This segmentation allows the tilting movement to be distributed across multiple sectors rather than occurring in a single large space, maintaining the desired tilting amplitude while eliminating the pinching hazard associated with large empty spaces.
2Object-affected harmful factors
If a bellows-shaped element with flexible structure is provided to surround the open area between supports to limit pinching risk, then the pinching risk is reduced, but the aesthetic appearance deteriorates and the element is subject to failure
Solution Approach 1:
Instead of using a single bellows-shaped covering element that degrades aesthetics, the invention segments the elastic device into multiple rigid sectors with slits between them. This segmentation inherently limits the empty space where pinching could occur, eliminating the need for aesthetic-detrimental flexible coverings while maintaining safety.
Solution Approach 2:
The invention replaces the bellows-shaped element, which is subject to failure and degradation, with a more durable segmented structure consisting of rigid sectors and slits. This new design eliminates the reliability issues associated with flexible coverings that are prone to failure.
3Object-affected harmful factors
If multiple sectors are provided in the elastic device with slits between them, then the pinching risk is eliminated and comfort is improved, but the device complexity increases
Solution Approach 1:
The elastic device is segmented into multiple sectors stacked on top of one another, with slits formed between adjacent sectors. While this segmentation increases structural complexity compared to a single-element design, it eliminates pinching risks and improves comfort by distributing the tilting movement across multiple sectors, each containing a portion of the elastic element.
Solution Approach 2:
The multiple sectors are arranged in a nested configuration, stacked on top of one another within the same spatial envelope. This nesting approach allows the complex multi-sector structure to be compact, reducing the overall space required while maintaining the safety and comfort benefits of segmentation.
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 eliminates the risk of pinching and provides improved user comfort by distributing the bending load across multiple sectors, eliminating the need for additional flexible coverings and enhancing aesthetic appeal.
Implementation Method 1
an elastic element having a top stretch fixed to the top support and a bottom stretch fixed to the bottom support, the elastic element being flexurally deformable to enable tilting between the top support and the bottom support
Implementation Method 2
each elastic device includes an elongated flat spring, the ends of which are fixed to a top support and to a bottom support
Data Source
AI summary
A chair comprising, a base structure including two rear tubular elements open at the top, a backrest having two tubular portions open at the bottom and aligned to said tubular elements of the base structure, and two elastic devices, each of which has a top support inserted in a tubular portion of the backrest, a bottom support inserted in the corresponding tubular element of the base structure, and an elastic element flexurally deformable to enable tilting between the top support and the bottom support, wherein each of said elastic devices comprises a plurality of sectors stacked on top of one another and arranged between the top support and the bottom support, and wherein, in a resting position of the elastic element, a plurality of slits are formed on the rear side of each elastic device between each pair of adjacent sectors.