Chair with a lockable hinge assembly and hinge assembly

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Solution Overview

Problem

Existing office chairs lack the ability to dynamically adjust seat movement while allowing selective locking of movements, particularly preventing backward rocking, which is essential for ergonomic comfort.

Innovation Solution

A chair with a joint arrangement featuring a locking device that includes a locking element with threads and an actuating element, allowing adjustable locking positions to restrict or permit movements, and a spring element providing restoring force, combined with a stop mechanism to prevent backward rocking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the joint arrangement allows continuous movement for dynamic sitting, then ergonomic comfort is improved, but the ability to prevent unwanted movements (especially backward rocking) deteriorates

Engineering Contradiction:
Improvedynamic sitting capabilityVSAvoidstability against backward rocking
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The locking element is designed to be movable between a locked position (preventing backward rocking) and a released position (allowing dynamic movement). The actuating element enables the user to dynamically switch between these states, making the system adaptable to different usage requirements while maintaining both stability and ergonomics

Inventive Principle:
Principle #15Dynamics

2Reliability

If a locking mechanism is added to prevent backward rocking, then stability is improved, but device complexity deteriorates

Engineering Contradiction:
Improvestability against backward rockingVSAvoidjoint arrangement complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking element is integrated into the existing joint arrangement and shares the same receptacle as the support connecting part and spring element. The actuating element is coupled to the locking element, allowing the locking function to be added without requiring separate housing or complex assembly structures

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The locking element serves multiple functions: it prevents backward rocking when engaged, allows forward movement when disengaged, and can be actuated by a simple user-operated element. The same structural components (receptacle, spring element) serve both the original support function and the new locking function

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

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The chair offers dynamic sitting with small movements while allowing selective locking, enhancing ergonomic comfort by preventing backward rocking and maintaining synchronous movement functionality.

Implementation Method 1

a support connecting part (13) which is movable relative to the seat part (2) against the restoring force of a spring element (14)

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 2

The locking element can have a through-hole for the support and an external thread that interacts with a corresponding internal thread of the base element

Methodology Applied
Scientific EffectScrew: Screw

Data Source

PatentEP4327698B1Chair with a lockable hinge assembly and hinge assembly
Publication Date: 2025.06.25 INTERSTUHL BUEROMOEBEL GMBH & CO KG
  • EP4327698B1 patent drawingFigure 1
  • EP4327698B1 patent drawingFigure 2
  • EP4327698B1 patent drawingFigure 3~4

AI summary

In a chair (1), in particular an office chair, with a seat (2) and a footrest, the footrest comprises a support (3) which is connected to the seat (2) via a joint arrangement (4) that allows relative movement between the seat (2) and the footrest. The joint arrangement (4) comprises a support connecting element (13) which is movable relative to the seat (2) against the restoring force of a spring element (14). Both the support connecting element (13) and the spring element (14) are arranged, at least partially, in a receptacle (11) which is bounded on the upper side by a top part (10) and on the lower side by a base element (12). A locking device (21), which is movable between a locking position and a release position, prevents relative movement between the support connecting element (13) and the seat (2) in a locking position.