Sofa Backrest Coupling Device with Truncated Cone Guide

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Solution Overview

Problem

Existing coupling mechanisms for sofa and armchair backrests face issues with accessibility and visibility of female guides, leading to improper fitting and complex, risky disassembly processes due to metal straps, which can cause operator injuries.

Innovation Solution

A truncated cone-shaped part is used to guide and secure the plate into the female guide, eliminating the need for metal straps and simplifying assembly by accommodating width variations in the plates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If female guides are placed in the frame structure to couple backrests, then assembly is simplified and no tools are required, but accessibility and visibility become poor leading to improper fitting

Engineering Contradiction:

Improveassembly simplicityVSAvoidaccessibility and visibility

Core Design Contradiction:

Ease of manufactureVSEase of operation

Solution Approach 1:

A plate is introduced as an intermediary component between the female guide and the backrest. This plate features a truncated cone-shaped guide that protrudes from the female guide, making the coupling interface accessible and visible while maintaining the tool-free assembly benefit. The plate acts as a mediator that bridges the gap between the hidden female guide and the external assembly operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If metal straps with spring-loaded latches are used to secure the coupling, then the backrest is prevented from detaching, but disassembly becomes complex and dangerous requiring great skill

Engineering Contradiction:

Improvecoupling securityVSAvoiddisassembly simplicity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The spring-loaded latch mechanism is completely removed from the coupling system. Instead, a simple plate with a truncated cone-shaped guide is used, which allows the backrest to be secured through friction and geometric fitting alone. This extraction of the complex latch mechanism eliminates the danger and skill requirement during disassembly while maintaining adequate coupling security for normal use.

Inventive Principle:

Principle #2Taking out (Extraction)

3Adaptability or versatility

If the truncated cone-shaped part is made wider at the base, then plates with width variations are accommodated, but the structure becomes more complex

Engineering Contradiction:

Improvewidth variation accommodationVSAvoidstructural complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

A truncated cone shape is employed instead of a cylindrical or rectangular guide. The conical geometry with its smooth curvature naturally accommodates width variations in plates through its tapered form, allowing plates of different widths to be guided into proper alignment. This curved geometric solution achieves adaptability without requiring complex adjustable mechanisms or multiple components.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Data Source

PatentEP4115772B1Coupling device for sofa and armchair backrests

Publication Date: 2025.10.29 FAMA SOFAS

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AI summary

Coupling device for sofa and armchair backrests comprising a relaxation mechanism configured to move the front of the sofa or armchair forward, transforming the front of the sofa into a footrest and tilting the backrest that comprises at least one truncated cone-shaped part (1,10) that can be coupled to at least one plate (3) of the relaxation mechanism.