Folding Chair Locking Interface for Stable Unfolded Position

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Solution Overview

Problem

Folding chairs lack a secure mechanism to lock the cross members in the unfolded position, leading to instability and potential collapse during use.

Innovation Solution

The folding chair incorporates a locking interface with upper and lower receiving portions and pivotally connected crossbar members, where the primary crossbar members are releasably retained within these interfaces, ensuring stability by deflecting tabs that engage the crossbar members when seated and release when folding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the folding chair uses a simple hinge connection without locking mechanism, then the device complexity is reduced, but the stability and reliability of the unfolded position deteriorates

Engineering Contradiction:

Improvelocking mechanism complexityVSAvoidstability of unfolded position

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent introduces a locking interface as an intermediary component between the crossbar member and the frame assembly. This locking interface includes receiving portions that engage with tabs on the crossbar member, acting as a mediator to transfer and secure the load path from the seat to the ground, thereby ensuring stability without requiring a complex active locking mechanism

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The locking interface is designed to automatically engage and lock the crossbar member in the unfolded position through its own structural features (receiving portions and tabs). The system self-locks when the crossbar is inserted, eliminating the need for separate locking actions or complex control mechanisms, thus maintaining simplicity while ensuring reliability

Inventive Principle:

Principle #25Self-service

2Reliability

If the folding chair includes a locking interface with receiving portions and tabs, then the stability in unfolded position is improved, but the device complexity increases

Engineering Contradiction:

Improvestability of unfolded positionVSAvoidlocking interface structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The locking interface is merged with the existing crossbar assembly rather than being a separate independent mechanism. The receiving portions are integrated into the crossbar member itself, and the tabs are formed as part of the crossbar structure, combining the locking function with the structural support function to minimize additional complexity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Instead of using a complex active locking mechanism that requires actuation, the patent inverts the approach by using a passive locking system where the crossbar member itself becomes the locking element through its geometric features (tabs and receiving portions). The simplicity is achieved by making the structural element perform the locking function rather than adding a separate locking device

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If the crossbar members are releasably retained in the locking interface, then the stability during use is improved, but the ease of operation for folding deteriorates

Engineering Contradiction:

Improvestability during useVSAvoidease of folding

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The locking interface is designed with dynamic characteristics that allow it to transition between locked and unlocked states. The receiving portions are designed to engage firmly during normal use (providing stability) but can be easily disengaged when force is applied during folding (providing ease of operation). The system adapts its locking strength based on the operational state

Inventive Principle:

Principle #15Dynamics

4Reliability

If the locking interface uses tabs that deflect to engage crossbar members, then the reliability of the locked position is improved, but the device complexity increases

Engineering Contradiction:

Improvesecurity of locked positionVSAvoidlocking mechanism structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The tabs in the locking interface are designed as flexible elements that can deflect during engagement and then spring back to secure the crossbar member. This flexibility allows the tabs to accommodate minor misalignments and provide a secure locking action without requiring complex adjustment mechanisms, achieving reliability through simple elastic deformation

Inventive Principle:

Principle #30Flexible shells and thin films

Data Source

PatentUS11986100B2Folding chair

Publication Date: 2024.05.21 WESTFIELD OUTDOORS

AI summary

A folding chair has a first frame assembly, a second frame assembly, a front crossbar assembly, and a rear crossbar assembly. The front crossbar assembly has a front primary crossbar member, a front upper secondary crossbar member, a front lower secondary crossbar member, and a locking interface. The locking interface has an upper receiving portion on one end of the channel and a lower receiving portion on an opposite end of the channel. When the folding chair is in the expanded position and the feet of the frame assemblies are supported on a support surface, the front primary crossbar member has an upward facing portion that is releasably retained in the upper receiving portion of the locking interface and a bottom facing portion that is releasably retained in the lower receiving portion of the locking interface.