Backrest Shell Structure for Dynamic Rib Load Absorption
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Solution Overview
Problem
Existing backrest designs for office chairs struggle to provide dynamic support that allows individual ribs to absorb higher loads while maintaining flexibility and following the movement of the central part, especially when the rib pitch is narrow.
Innovation Solution
The design features a central part with elongated openings in the transverse direction, which connects the ribs via two webs, allowing for flexibility and deformation along a longer line, and includes a division into thirds with specific spacing and curvature to distribute load effectively, along with padding for comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If narrow ribs are used to increase flexibility and follow back movements, then the backrest can better adapt to spine curvature, but the individual ribs become sensitive to loads and cannot absorb higher individual loads
Solution Approach 1:
The patent merges adjacent ribs into rib pairs or groups that move together as a unit. This is achieved by providing connections between adjacent ribs at their rear ends, causing them to bend and move collectively. This merging increases the load-bearing capacity of each rib unit while preserving the overall flexibility and adaptability to back curvature through the segmented structure.
2Stability of the object's composition
If the central part is made continuous and plate-like to increase stability, then structural strength is improved, but comfort is reduced and the structure becomes heavier
Solution Approach 1:
The central part is segmented into multiple web areas separated by elongated openings, transforming it from a continuous plate into a lattice-like structure. This segmentation reduces weight and improves comfort by allowing flexibility and movement, while the distributed web areas maintain structural stability through their collective arrangement and connection to ribs.
3Strength
If ribs are made larger in longitudinal dimension to increase load capacity, then individual load absorption improves, but mobility is impeded by curvature changes of the central part
Solution Approach 1:
The patent creates a dynamic connection between ribs and the central part through elastic webs that allow relative movement. The ribs are designed to be movable relative to the central part, enabling them to maintain larger dimensions for load capacity while still accommodating curvature changes through elastic deformation and controlled mobility at the connection points.
4Strength
If the shell material is made thicker to increase rigidity, then structural strength is improved, but flexibility and ability to follow back movements is reduced
Solution Approach 1:
The shell is segmented into a lattice structure with multiple web areas and openings, which provides rigidity through the distributed framework while maintaining flexibility through the articulated connections between segments. This segmentation allows the structure to achieve both strength and adaptability without requiring increased material thickness.
Solution Approach 2:
The shell incorporates dynamic elements including movable ribs, elastic webs, and articulated connections that enable the structure to adapt its rigidity and flexibility based on applied loads and movement requirements, eliminating the need for uniformly thicker material throughout the shell.
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 enhances the rigidity and flexibility of the backrest, allowing it to absorb changes in curvature and distribute load efficiently, providing better support and comfort by ensuring the ribs and central part deform together, thus improving the overall dynamic support and load absorption.
Implementation Method 1
a backrest (11) for a passenger seat, in particular an office chair, which has an elastically deformable shell (11)
Data Source
Figure 1~4
Figure 5
Figure 6
AI summary
The shell (11) has a middle section (19) supporting a back in a longitudinal direction and includes a set of ribs (15) that laterally protrude in the transverse direction from the middle section. The ribs are separated from each other by lateral notches (17) and are bent forward, and movable against each other. Openings (21) are formed in the middle section, where opening run in transverse direction and stop between ends of lateral notches adjoining in longitudinal direction. Ends of notches and the ends of the openings lie in two regions.