chair

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Solution Overview

Problem

Existing furniture assembly methods require tools or substantial body strength, and existing joints lack robustness to withstand complex loads, particularly in self-assembly furniture like chairs.

Innovation Solution

A chair design featuring interlocking joint arrangements made of male and female parts that can be assembled without tools, using dowels with radial rims and recesses with corresponding grooves, allowing for secure and robust connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If mechanical fastening means are used to join furniture parts, then the joint strength and robustness are improved, but the ease of assembly deteriorates as tools and substantial body strength are required

Engineering Contradiction:
Improvejoint strengthVSAvoidease of assembly
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The joint arrangement enables self-service assembly through the interaction between male and female parts with dowels and recesses. The dowels automatically engage with the recesses when parts are brought together, eliminating the need for tools or substantial body strength while maintaining robust joint strength.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The male part with dowel is nested within the female part with recess, creating an interlocking joint arrangement. The dowel fits into the recess to form a secure connection that provides both ease of assembly and joint strength.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Ease of operation

If simple joint arrangements are used for self-assembly furniture, then the ease of assembly is improved, but the robustness and ability to withstand complex loads deteriorates

Engineering Contradiction:
Improveease of assemblyVSAvoidrobustness
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The joint arrangement combines multiple elements (male part, female part, dowel, recess) into a composite structure that provides both ease of assembly and robustness. The combination of these elements creates a joint that can withstand complex loads while remaining simple to assemble.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The joint is segmented into distinct male and female parts with dowels and recesses, allowing for easy assembly while maintaining structural integrity. This segmentation enables the joint to handle complex loads through the distributed connection points.

Inventive Principle:
Principle #1Segmentation

3Reliability

If multiple male and female parts are used in joint arrangements, then the robustness and prevention of rotation are improved, but the device complexity increases

Engineering Contradiction:
ImproverobustnessVSAvoidjoint complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Multiple dowels are merged into a single male part and multiple recesses are integrated into a single female part. This combining approach maintains the robustness provided by multiple connection points while reducing the overall number of separate components, thereby simplifying the joint arrangement.

Inventive Principle:
Principle #5Merging (Combining)

4Ease of operation

If furniture parts are designed for easy disassembly, then the ease of operation is improved, but the joint strength may deteriorate

Engineering Contradiction:
Improveease of disassemblyVSAvoidjoint strength
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The joint arrangement enables self-service both for assembly and disassembly. The same interlocking mechanism that provides strong joints during assembly also allows for easy disassembly by simply reversing the insertion motion, maintaining both strength and ease of operation.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3723552B1chair
Publication Date: 2025.04.09 INTER IKEA SYST
  • EP3723552B1 patent drawingFigure 1A
  • EP3723552B1 patent drawingFigure 1B~1C
  • EP3723552B1 patent drawingFigure 1D~1E

AI summary

The disclosure relates to a chair comprising a first and a second section (100A, 100B) mutually displaced from each other to form a gap (G) there between. A first cross-member (200A) is configured to connect with its first free end (201A) to the first section (100A) and with its second free end (201B) to the second section (100B), thereby bridging the gap (G). A first joint arrangement (500) is configured to attach the first free end (201A) to the first section (100A) and a second joint arrangement (600) is configured to attach the second free end (201B) to the second section (100A). Each of the first and second joint arrangements (500, 600) comprises a male part (520) in the form of a dowel (521) and a female part (537) in the form of a recess (531). The recess (531) has an elongated extension and a locking portion (533). The first cross-member (200A) is configured to be moved relative to the first and second sections (100A, 100B) such that the dowels (521) are moved along the elongated extension of the recesses (531) to the locking portions (533).