Double-Shell School Chair Seat for Dynamic Sitting Support
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Solution Overview
Problem
Conventional chairs lack the necessary flexibility and resilience to support dynamic sitting, which involves frequent changes in sitting position, especially under heavy loads commonly encountered in school settings.
Innovation Solution
A student chair with a tubular support frame and a double-shell plastic seat featuring stiffening ribs with a triangular cross-section extending from the seat part to the backrest, providing enhanced structural integrity and aesthetics, while the support frame is designed as a cantilever with U-shaped frame parts and a convex web for improved flexibility and stackability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the seat is made from a robust plastic material to withstand heavy loads, then the strength and durability are improved, but the flexibility and elasticity required for dynamic sitting deteriorate
Solution Approach 1:
The patent applies local quality by providing stiffening ribs only in specific critical areas where structural support is most needed, rather than making the entire seat rigid. The ribs are positioned to reinforce the transition area between seat part and backrest, and to maintain the overall shape under load, while leaving other areas sufficiently flexible to allow dynamic sitting movements.
Solution Approach 2:
The patent employs composite material construction by combining a robust plastic base material with integrated stiffening ribs that create a composite structure. This composite design allows different regions of the seat to have different mechanical properties - rigid in areas requiring support and flexibility in areas requiring movement - thus resolving the contradiction between overall strength and local flexibility.
2Strength
If reinforcing edges are added to the seat edges to increase strength, then the structural integrity is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges the reinforcing elements with the seat structure itself by integrating the stiffening ribs directly into the molded seat body. Rather than adding separate reinforcing edges as attachments or overlays, the ribs are formed as part of the single-piece molded construction, combining the seat shell and reinforcement into one unified component that reduces manufacturing steps and assembly complexity.
Solution Approach 2:
The patent applies segmentation by dividing the seat structure into functional zones through the strategic placement of stiffening ribs. The ribs segment the seat into areas of high structural requirement (where ribs are present) and areas of flexibility (between ribs), allowing strength to be provided only where necessary without requiring reinforcement throughout the entire seat structure.
3Stability of the object's composition
If the angle between seat part and backrest is made fixed to maintain proper positioning, then the stability is improved, but the ability to support dynamic sitting movements deteriorates
Solution Approach 1:
The patent applies local quality by providing targeted stiffening ribs in the transition area between the seat part and backrest, rather than making the entire connection rigid. This localized reinforcement maintains the angle stability where needed while allowing controlled flexibility in other areas to accommodate dynamic sitting movements and position changes.
Solution Approach 2:
The patent embodies dynamics by designing a structure that is neither completely rigid nor completely flexible. The stiffening ribs provide dynamic stability - maintaining the essential angle relationship between seat and backrest while allowing controlled movement and adaptation to accommodate changing load conditions and user movements during dynamic sitting.
Data Source
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AI summary
A seat (2) on a school-pupil's chair is molded as a double-shell plastic mold with two or more stiffening ribs (24) extending from a seat part's (20) underside to a backrest's (22) rear side. The stiffening ribs form a side edge for the chair in a transitional area from the backrest to the seat part.