Convertible Sofa-Bed Linkage for Compact Hidden Mechanisms

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Solution Overview

Problem

Traditional sofa beds face challenges in providing both comfortable sofa and bed functionality with reduced dimensions, complex mechanisms, and aesthetic limitations, often compromising on posture and styling due to bulky mechanisms that are difficult to hide.

Innovation Solution

A convertible furniture design featuring a bed member that tilts onto a sofa member using an articulated system with a reduced number of components, allowing seamless conversion between positions while hiding the mechanism, ensuring optimal height and self-supporting functionality without wall fixation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional sofa bed mechanisms are used to provide both sofa and bed functionality, then the furniture can convert between positions, but the mechanism becomes bulky and aesthetically limiting

Engineering Contradiction:
Improvesofa-bed conversion capabilityVSAvoidmechanism bulk and visibility
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The sofa bed mechanism is divided into separate functional modules: the seat assembly with its own support structure, the bed base with independent hinges, and the backrest section. This segmentation allows each component to be optimized independently and reduces the overall complexity of the conversion mechanism.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The seat assembly is designed to nest within or alongside the bed base structure during conversion. The seat support elements are positioned to occupy the same spatial envelope as the bed mechanism, effectively hiding the sofa bed complexity within the overall furniture form.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Volume of moving object

If the mechanism is made compact to reduce dimensions, then the sofa position size is reduced, but the mechanism becomes more complex

Engineering Contradiction:
Improvesofa position dimensionsVSAvoidmechanism complexity
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The mechanism uses dynamic positioning where the seat and bed base move relative to each other during conversion. The hinges and support elements are designed to shift positions based on whether the furniture is in sofa mode or bed mode, allowing compact storage in the sofa position without requiring overly complex fixed-geometry mechanisms.

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If the seat is lowered to improve sofa comfort, then the sitting position is optimized, but the conversion mechanism becomes more complex

Engineering Contradiction:
Improvesofa sitting comfortVSAvoidseat movement mechanism
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The seat lowering function is merged with the bed base raising function into a single conversion action. When the bed base is lifted to its operational position, the seat naturally lowers or adjusts position as a coupled movement, eliminating the need for separate seat adjustment mechanisms and reducing overall complexity.

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 design achieves quick, easy, and reliable conversion between sofa and bed positions with optimal height alignment, hiding the mechanism for aesthetic appeal and reduced manufacturing costs, while maintaining comfort and styling flexibility.

Implementation Method 1

The bed base 5 and the frame 7 are mutually pivoted and can tilt with respect to a supporting framework 9

Methodology Applied
Scientific EffectHinge: Hinge

Implementation Method 2

The bed base 5 with the bracket 13, the frame 7 and the lever 15 constitute a system that is articulated to the supporting framework 9

Methodology Applied
Scientific EffectLever: Lever

Data Source

PatentEP2838400B1Convertible piece of furniture, from sofa use to bed use and vice versa
Publication Date: 2016.03.09 CLEI SRL
  • EP2838400B1 patent drawingFigure 1
  • EP2838400B1 patent drawingFigure 2~3
  • EP2838400B1 patent drawingFigure 4~5

AI summary

A convertible piece of furniture (1), from sofa use to bed use and vice versa, having a framework (9) that supports a bed member (2) that can be tilted onto a sofa member (3) in at least two working positions: a day position, in which the bed member (2) is in a vertical position and the sofa member (3) can be used for sitting, and a night position, in which the bed member (2) is rotated in a horizontal position and surmounts the sofa member (3). The piece of furniture (1) is characterized in that it includes an articulated system that connects the bed member (2) to the sofa (3) and to the framework. The bed member (2) forms a lying surface in the night position, while the sofa member (3) forms a sitting surface in the day position. The lying surface of the bed member (2) substantially corresponds to the sitting surface of the sofa member (3). The sofa member (3) forms, in the night position, a retracted surface that is different from the sitting surface.