Chair Slide-In Coupling for Hidden Backrest Assembly Without Fasteners

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Solution Overview

Problem

The existing methods for manufacturing chairs with backrests and side elements, which involve welding or fasteners, are complex, costly, and aesthetically detrimental due to exposed seams or fasteners.

Innovation Solution

A chair design featuring a slide-in coupling between the backrest and side elements, where the backrest is connected through vertically located slots and coupling elements, eliminating the need for visible fasteners and simplifying the assembly process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If welding or fasteners are used to connect the back rest with side elements, then the connection strength is improved, but the appearance is deteriorated due to exposed seams or fasteners

Engineering Contradiction:
Improveconnection strengthVSAvoidappearance
Core Design Contradiction:
StrengthVSShape

Solution Approach 1:

The coupling element is inserted into the rear leg and hidden within its structure. The coupling element comprises a protrusion that extends into the rear leg, creating a nested configuration where the connection components are contained within the leg rather than exposed on the surface, thus maintaining both strength and aesthetic appearance.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If welding or fasteners are used to connect the back rest with side elements, then the connection reliability is improved, but the manufacturing complexity and cost are increased

Engineering Contradiction:
Improveconnection reliabilityVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention replaces complex welding processes or multiple fastener assemblies with a simple slide-in coupling mechanism. The coupling element with protrusion slides into the rear leg and is retained by an undercut, creating a reliable mechanical connection through a single straightforward assembly motion rather than requiring welding equipment or multiple fastening operations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The coupling element features an undercut that automatically retains the element in place once inserted into the rear leg. The undercut geometry creates a self-locking mechanism where the protrusion of the coupling element engages with the rear leg structure, providing self-retention without requiring additional fasteners, clips, or complex assembly steps.

Inventive Principle:
Principle #25Self-service

3Strength

If welding or fasteners are used to connect the back rest with side elements, then the connection strength is improved, but the ease of operation is deteriorated due to difficult assembly process

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

Solution Approach 1:

The invention replaces complex welding processes or multiple fastener assemblies with a simple slide-in coupling mechanism. The coupling element with protrusion slides into the rear leg and is retained by an undercut, creating a reliable mechanical connection through a single straightforward assembly motion rather than requiring welding equipment or multiple fastening operations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP3248509B1Chair and method for the manufacturing of a chair
Publication Date: 2020.07.08 ZHEJIANG YOTRIO GRP CO LTD
  • EP3248509B1 patent drawingFigure 1
  • EP3248509B1 patent drawingFigure 2
  • EP3248509B1 patent drawingFigure 3

AI summary

A chair and a method for the manufacturing of a chair are presented. The chair comprises a sitting surface (1), a back rest (2) and two side elements (3). The sitting surface (1) is fixed between the side elements (3). Each side element (3) comprises a front leg (31) and a rear leg (32), and the back rest (2) is connected with each rear leg (32) through a slide-in coupling.