Elastic Textile Backrest Assembly for Modular Chair Frames

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Solution Overview

Problem

The existing chair designs with a one-piece knitted fabric covering for both the seat and backrest have complex assembly processes and limited design options due to the uniform design, making it difficult to achieve comfort and ease of attachment while allowing for variation in the seat area and base design.

Innovation Solution

A chair design where the textile covering is pushed over the upper backrest bars of a prefabricated frame without initial stretching, utilizing the elasticity of the material for width and height tightening, with a head piece attached under the tension of the spring forces of the bars to secure it, allowing for easier assembly and greater design flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a one-piece knitted fabric covering is used for both seat and backrest, then comfort is improved, but assembly complexity increases and design flexibility is reduced

Engineering Contradiction:
ImprovecomfortVSAvoidassembly complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent divides the chair into modular components: a prefabricated frame with integrated backrest bars, a separate textile covering, and a head piece. This segmentation allows the covering to be pushed over the backrest bars independently, simplifying assembly while maintaining comfort through the textile material.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The backrest bars are pre-configured with a smaller distance between them, allowing the covering to be pushed on easily before final assembly. The head piece is then attached, and finally the bars are spread to their larger operational distance, which tensions the covering and secures it in place.

Inventive Principle:
Principle #10Preliminary action

2Ease of manufacture

If the covering is pushed over the backrest bars without initial stretching, then ease of manufacture is improved, but the covering must be elastic to achieve proper tensioning

Engineering Contradiction:
Improveease of attachmentVSAvoidmaterial elasticity requirement
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent utilizes the elastic properties of the textile material by changing the physical state of the backrest bars during assembly. The bars are positioned at a smaller distance initially for easy covering installation, then spread to a larger distance to tension the covering, exploiting the material's elastic recovery to achieve secure fastening.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If the backrest and seat area have uniform design, then manufacturing is simplified, but design options are limited

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoiddesign options
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent applies different design treatments to different parts of the chair. The backrest area uses the textile covering pushed over the bars, while the seat area can have different configurations. The head piece can be designed in various styles, and the base can be varied independently, allowing design diversity without complicating the core manufacturing process.

Inventive Principle:
Principle #3Local quality

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

The solution simplifies the attachment process and enhances design possibilities by utilizing the elasticity of the textile material for both width and height tensioning, providing a secure and comfortable seating experience while allowing for varied seat and base designs.

Implementation Method 1

which is possible due to the elasticity of its material

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The head piece is thus under the tension of the spring forces of the bars, which can be used to secure the head piece to the bars

Methodology Applied
Scientific EffectSpring force: Spring

Data Source

PatentEP2165628B1Chair with back rest and method for its manufacture
Publication Date: 2011.04.13 ALFONS VENJAKOB GMBH & CO KG
  • EP2165628B1 patent drawingFigure 1~2
  • EP2165628B1 patent drawingFigure 3~4

AI summary

The chair has upright bars (8) arranged at a distance from each other. A covering (11) made of elastic textile material and provided between the bars has a hem-stitching (12) at its upright edges. The bars are passed through the covering and fixed at a chair frame with its lower ends. The bars are resiliently flexible and provided with a spring tension acting on top of the bars in the direction of the surfaces tensed by the covering. Upper ends (9) of the bars have retainers (16-18), and a head piece (15) is attached at the retainers for forcing the bars against spring force.