Nested Footrest Linkage Design to Reduce Sofa Retracted Thickness
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Solution Overview
Problem
Current multi-functional sofas have a bulky and aesthetically unpleasing retracted position due to large mechanical extending linkages, and their extended footrest length is insufficient for comfort.
Innovation Solution
A mechanical extending linkage system with a footrest assembly comprising primary and secondary footrests, intermediate links, and a seat assembly that allows for parallel alignment of links in the retracted position, reducing thickness and enabling extended length when needed, along with a backrest assembly for adjustable recline positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the mechanical extending linkage is designed to provide extended footrest function, then the footrest extension length is increased, but the thickness of the retracted position becomes larger
Solution Approach 1:
The patent implements a nested linkage structure where the secondary footrest linkage is integrated within the primary footrest linkage. When retracted, the secondary linkage folds into the space occupied by the primary linkage, allowing both linkages to occupy minimal space while still providing extended footrest length when deployed. This nesting approach resolves the contradiction by enabling long extension capability without increasing retracted thickness.
Solution Approach 2:
The patent transitions from a single-plane linkage to a multi-dimensional arrangement where links are positioned at different heights and angles. The intermediate links connect the primary and secondary footrest linkages in a three-dimensional configuration, allowing the mechanism to achieve extended length in the horizontal direction while maintaining compact thickness in the vertical direction when retracted.
2Length of moving object
If the mechanical extending linkage is designed to provide extended footrest function, then the footrest extension length is increased, but the appearance becomes uglier and more complex
Solution Approach 1:
The patent merges the primary and secondary footrest linkages into a unified mechanical system that operates as a single integrated unit. The intermediate links connect the two linkages in such a way that they move cooperatively, creating a streamlined appearance rather than two separate mechanisms. This merging approach maintains aesthetic simplicity while achieving extended footrest length.
Solution Approach 2:
The patent applies different structural characteristics to different parts of the linkage system. The primary linkage uses robust, visible components for structural support, while the secondary linkage and intermediate links use more compact, concealed arrangements. This local differentiation allows the main visible structure to remain simple and aesthetically pleasing while the extended functionality is achieved through less visible secondary elements.
3Length of moving object
If the mechanical extending linkage is designed to provide extended footrest function, then the footrest extension length is increased, but the device complexity increases
Solution Approach 1:
The patent divides the footrest extension mechanism into segmented components: primary linkage, secondary linkage, and intermediate links. Each segment performs a specific function and can be independently analyzed and manufactured. This segmentation reduces overall complexity by breaking down the complex motion into simpler, manageable segments that work together through well-defined connection points.
Solution Approach 2:
The intermediate links serve multiple functions simultaneously: they connect the primary and secondary linkages, transmit mechanical forces between them, and guide the relative motion. This multi-functionality reduces the need for additional specialized components, thereby reducing overall device complexity while achieving the extended footrest length objective.
Data Source
AI summary
A mechanical extending linkage is configured to be mounted in a seating unit capable of being moved between a retracted position and an extended position and comprising a seat, a backrest and extendable primary and secondary footrests. The mechanical extending linkage comprises a footrest assembly for extending and retracting the primary footrest and the secondary footrest, the footrest assembly comprising a primary footrest link, a secondary footrest link, and an intermediate link set having a first intermediate link, a second intermediate link, a third intermediate link and a fourth intermediate link. The footrest assembly is configured in such a manner that the secondary footrest link, the first intermediate link and the second intermediate link are arranged substantially parallel with the seat when the seating unit is in the retracted position.