J-Shaped Backrest and Armrest Joining System for Modular Furniture

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Solution Overview

Problem

Existing modular sofa and armchair joining systems are complex to assemble and disassemble, often requiring excessive strength and being prone to jamming, especially with removable upholstery, leading to unstable and durable joints.

Innovation Solution

A J-shaped flat and curved part with an internal cut-out that fits into a circular part, secured by screws, allowing easy assembly and disassembly with minimal force, and featuring a protruding pivot for precise alignment and fixation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If crossbow or eyelet systems are used for joining sofa parts, then the joints are strong once assembled, but the assembly and disassembly process becomes complex and difficult to handle

Engineering Contradiction:
Improvejoint strengthVSAvoidassembly ease
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The joining system is divided into two distinct components: a circular part fixed to the sofa structure and a J-shaped part attached to removable components. This segmentation allows each part to be optimized independently - the circular part provides a stable anchoring point while the J-shaped part enables easy insertion and removal through its geometric design, resolving the contradiction between joint strength and assembly ease.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The J-shaped part acts as an intermediary element that mediates between the user's manual operation and the fixed circular part. Its specific geometry with the cut-out section allows it to engage with the circular part in a controlled manner, providing both the necessary connection strength and the ease of operation through intuitive alignment and insertion without requiring complex alignment procedures.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If traditional eyelet systems are used, then the joints provide strong connection, but the parts tend to jam during disassembly requiring excessive strength

Engineering Contradiction:
Improveconnection strengthVSAvoiddisassembly force
Core Design Contradiction:
StrengthVSForce

Solution Approach 1:

The design inverts the traditional eyelet mechanism by having the J-shaped part (attached to removable components) engage with the circular part (fixed to structure) in reverse orientation. The J-shaped part inserts into the circular part rather than the circular part being pulled through, allowing disassembly by simply reversing the insertion motion. This inversion eliminates jamming issues and reduces disassembly force while maintaining connection strength.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The circular part and J-shaped part utilize curved geometries that facilitate smooth engagement and disengagement. The rounded contours reduce friction and prevent jamming during the insertion and removal processes, allowing users to assemble and disassemble components with minimal force while maintaining strong connections when assembled.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Ease of operation

If upholstery with Velcro is added for removable covers, then the upholstery is easily removable, but the assembly complexity increases due to additional thickness and alignment difficulty

Engineering Contradiction:
Improveupholstery removabilityVSAvoidassembly complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The circular-J-shaped joining system serves multiple functions: it provides structural connection for rigid components, accommodates the additional thickness from upholstery and Velcro layers, and maintains alignment guidance throughout the assembly process. This universal design handles both the upholstery attachment function and the structural joining function through the same mechanism, preventing complexity multiplication.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The circular part is pre-fixed to the sofa structure during manufacturing, and the J-shaped parts are pre-attached to removable components. This preliminary action ensures that during final assembly, users only need to perform the simple insertion motion of the J-shaped parts into the circular parts, without needing to align multiple components or deal with thickness variations, thereby reducing overall assembly complexity.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4635370A1Backrest and armrest fixing system for furniture
Publication Date: 2025.10.22 FAMA SOFAS
  • EP4635370A1 patent drawingFigure 1~2
  • EP4635370A1 patent drawingFigure 3
  • EP4635370A1 patent drawing

AI summary

The present invention relates to a system for joining backrests and arms in furnishing comprising a J-shaped flat and curved part (1), with an internal cut-out, which allows the insertion into the circular part (2) by means of a forward and downward movement to fit into the joining system.