Parallelogram Sofa Bed Linkage for Easier Seat-to-Lounger Conversion
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Solution Overview
Problem
Conventional seating or reclining furniture designs often compromise on comfort in the sitting position due to a wide seat surface required for a sufficient lying surface in the reclining position, as the back cushion is not attached to the frame and must be removed or moved, leading to inefficient and potentially injurious conversions.
Innovation Solution
The furniture features a seat cushion element and an additional cushion element connected via parallelogram linkages, with the back cushion attached to the frame, allowing the seat cushion to move horizontally along a sliding strip, shortening the conversion path and enabling comfortable sitting while maintaining a sufficient lying surface by articulating the additional cushion element on transverse arms of the parallelogram linkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the back cushion is not attached to the furniture frame and is removed before conversion, then the seat cushion element can be raised and folded out, but the conversion process becomes complex and potentially injurious
Solution Approach 1:
The back cushion is pre-attached to the furniture frame in a fixed position, eliminating the need to remove or reposition it during conversion. This preliminary positioning allows the seat cushion element to be directly raised and folded out without complex removal steps, simplifying the conversion process while maintaining ease of operation
Solution Approach 2:
The problem of back cushion interference is solved by extracting the back cushion from the conversion process entirely. By permanently attaching it to the frame, the back cushion is removed from the moving components, allowing the seat cushion element to convert independently without the complexity of coordinating back cushion movement
2Area of stationary object
If the seat cushion element is designed to be wide for sufficient lying surface, then the lying surface is adequate, but the seat surface becomes too wide for comfortable sitting
Solution Approach 1:
The seat cushion element is designed with dynamic dimensions that change based on configuration. In sitting position, it maintains a narrower width for comfort. During conversion, it expands horizontally to provide sufficient lying surface area. This dynamic dimensional change resolves the contradiction between sitting comfort and lying surface adequacy
Solution Approach 2:
The seat cushion element is segmented into multiple sections that can independently adjust their positions and dimensions. This segmentation allows the cushion to maintain a compact, comfortable width for sitting while expanding to provide adequate lying surface area when converted, effectively separating the functional requirements of the two usage modes
3Area of stationary object
If the seat cushion element is raised through large vertical movements, then the lying surface can be formed, but heavy furniture parts must be moved with great effort
Solution Approach 1:
Instead of raising the seat cushion element through large vertical movements, the conversion mechanism utilizes horizontal displacement along guide rails. This dimensional change from vertical to horizontal movement reduces the effort required, as the seat cushion element slides horizontally rather than being lifted against gravity, while still achieving the necessary lying surface formation
Solution Approach 2:
The conversion mechanism is designed to move the seat cushion element along an equipotential path where possible, minimizing changes in gravitational potential energy. By using horizontal sliding movements rather than vertical lifting, the system maintains constant gravitational potential, reducing the effort required to convert the furniture while still achieving adequate lying surface area
Data Source
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AI summary
The furniture has parallelogram arm (7) to transfer seat cushion element (1) between seated position and lying position. The seat cushion element is made to lie above auxiliary cushion element (2) and furniture frame (4), and is partially covered by back cushion (3), in seated position. The seat cushion element is arranged in horizontal position relative to auxiliary cushion element, in lying position. The seat cushion element is moved along vertical direction by the arm, and then moved along horizontal direction so as to be seated above auxiliary cushion element.