Foldable Seat Hinge Locking Mechanism

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Solution Overview

Problem

Conventional foldable seats for rollators and wheelchairs are complex, costly, and unsafe, as they cannot be locked in a folded position and may unintentionally unlock when the user is sitting, leading to discomfort and increased production costs.

Innovation Solution

A foldable seat design with a locking/unlocking system integrated within the hinge, featuring a cylindrical locking element and button/strap mechanism that allows easy locking and unlocking while preventing unwanted unlocking, ensuring the seat remains secure in both unfolded and folded positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If locking means are positioned externally (above the top surface of the seating structure), then the seat can be locked in the unfolded position, but the strap causes discomfort to users and requires increased production costs

Engineering Contradiction:
Improvelocking reliabilityVSAvoiduser discomfort
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The locking means are nested within the hinge mechanism itself, specifically positioned inside the hollow cylindrical body of the hinge. The locking element is received within the hinge structure, eliminating the need for external straps or components that protrude above the seat surface. This resolves the contradiction by maintaining locking reliability while eliminating user discomfort from external components.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If conventional locking means are used, then the seat can be locked in the unfolded position, but the user cannot lock the seating structure in a folded position

Engineering Contradiction:
Improvelocking capabilityVSAvoidposition locking versatility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The locking element is designed to be movable along the longitudinal axis of the hinge, allowing it to engage with different locking surfaces depending on the seat position. The spring means provides dynamic force to maintain engagement. This enables the same locking mechanism to securely lock the seat in both unfolded and folded positions, achieving position locking versatility.

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If the locking element is positioned externally, then it can be easily accessed, but unwanted unlocking may occur when the user is sitting on the locking element

Engineering Contradiction:
Improvelocking accessibilityVSAvoidunwanted unlocking risk
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The locking element is nested within the hollow cylindrical body of the hinge, making it inaccessible to users sitting on the seat. The unlocking element extends through the hinge structure, allowing intentional unlocking only when deliberately actuated. This resolves the contradiction by preventing unwanted unlocking while maintaining reliable locking, as the locking mechanism remains protected from accidental activation.

Inventive Principle:
Principle #7Nested doll (Nesting)

4Reliability

If complex locking systems with multiple components are used, then reliable locking can be achieved, but the device complexity and production costs increase

Engineering Contradiction:
Improvelocking reliabilityVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking means are merged with the hinge mechanism, combining two separate functions (hinging and locking) into a single integrated structure. The locking element, spring means, and unlocking element are all incorporated within the hinge assembly, eliminating the need for separate external locking components. This reduces device complexity and production costs while maintaining locking reliability.

Inventive Principle:
Principle #5Merging (Combining)

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 solution provides a simple, compact, and safe mechanism for users to easily lock and unlock the seat, preventing unintended folding or unlocking, thus enhancing user safety and reducing production costs by eliminating the need for external straps or complex components.

Implementation Method 1

said locking element being movable under the action of a spring means

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP2537503B9Foldable seat for a rollator or a wheelchair
Publication Date: 2015.01.21 INVACARE INT
  • EP2537503B9 patent drawingFigure 1~2b
  • EP2537503B9 patent drawingFigure 3
  • EP2537503B9 patent drawingFigure 4~6

AI summary

The invention concerns a foldable seat (1) for a rollator or a wheelchair, said seat comprising: - a first rigid plate (2) and a second rigid plate (3), said plates being adjacently connected along a longitudinal axis (XX') so as to be rotatably moveable around said longitudinal axis (XX') between an unfolded position, in which their plane surfaces (2a, 3a) are approximately aligned, and a folded position, in which their plane surfaces (2a, 3a) define an angle less than 180°, and preferably, an angle approximately equal to zero, said plates (2, 3) being also configured so as to be pivotally connectable to a frame of a rollator or a wheelchair, and - a hinge (10) pivotally connecting said first plate (2) to said second plate (3), wherein said hinge (10) comprises at least a first cylinder (11) integral with said first plate (2), said first plate (2) projecting over said first cylinder (11), at least a second cylinder (12) integral with said second plate (3), said second plate (3) projecting over said second cylinder (12), and a pivot pin (14) extending through axial through-bores and/or apertures (11c, 12c) of said first and second cylinders (11, 12), said pin (14) defining said longitudinal axis (XX'), characterized in that said seat (1) further comprises a locking/unlocking system (20) configured to be actuated by hand by the user so as to lock, respectively unlock, said first and second plates (2, 3) into, respectively from, said unfolded position and/or said folded position, said locking/unlocking system (20) being at least partially lodged inside said first and/or said second cylinder (11, 12).