Sofa-Bed Elastomeric Tie Rod Design to Reduce Opening Force and Noise
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Solution Overview
Problem
Sofa-beds with metal spiral springs require significant user effort to open and close, are uncomfortable due to abrupt movements, generate noise, and suffer from mechanical deformation over time, with high production costs and replacement difficulties.
Innovation Solution
The use of elastomeric tie rods, made from materials like polyisoprene, replaces metal spiral springs, providing a more fluid and effortless opening and closing mechanism, reducing noise, and maintaining mechanical stability and reliability with easier manufacturing and replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If metal spiral springs are used to connect the foldable frame to the fixed frame, then the sofa-bed can switch between sofa and bed configurations, but significant forces are required from the user to open and close the sofa-bed
Solution Approach 1:
The patent applies counterweight principle by positioning the springs to counterbalance the weight of the movable frame components. The springs are arranged to provide upward counteracting force against the downward weight force during transitional steps, reducing the net force the user must apply to open or close the sofa-bed.
Solution Approach 2:
The patent implements dynamics by using a pair of opposing springs that dynamically change their state between tension and rest during the opening and closing cycle. This dynamic configuration allows the springs to adaptively provide assistance throughout the movement range, making operation easier across all phases.
2Stability of the object's composition
If metal spiral springs are used in the sofa-bed mechanism, then the foldable frame can be supported, but abrupt movements occur during lengthening and shortening
Solution Approach 1:
The dynamic configuration of opposing springs allows for smooth transitions by having one spring in tension while the other is at rest, and vice versa during the cycle. This dynamic alternation prevents abrupt movements and provides fluid operation while maintaining mechanical stability throughout the range of motion.
3Reliability
If metal spiral springs are used to enable sofa-bed transformation, then the mechanism functions properly, but strong sudden metallic noises and squeaks are generated
Solution Approach 1:
The patent introduces an intermediary element (the specific spring configuration and mounting arrangement) between the moving frame components and the fixed frame. This intermediary system absorbs and dampens the sudden impacts and friction that generate metallic noises, while still providing the necessary mechanical support and functionality.
4Productivity
If metal spiral springs are used in the sofa-bed, then the opening and closing mechanism works, but the springs deform plastically or change mechanical performance over time
Solution Approach 1:
The counterweight arrangement with opposing springs distributes the mechanical stress more evenly and prevents excessive loading in any single direction. This reduces plastic deformation and maintains consistent mechanical performance over time, improving long-term reliability while preserving operational functionality.
5Reliability
If metal spiral springs are used to provide mechanical support in the sofa-bed, then the transformation mechanism functions, but production costs increase and replacement becomes difficult
Solution Approach 1:
The patent employs an intermediary spring configuration that can be more easily manufactured and replaced. The design allows for standardized spring components that are simpler to produce and install, reducing manufacturing costs and facilitating easier maintenance while still providing the necessary mechanical support for sofa-bed transformation.
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 elastomeric tie rods significantly reduce the force required for opening and closing, provide a smooth and quiet operation, maintain mechanical stability over time, and lower production costs, while being safer and easier to replace than traditional metal springs.
Implementation Method 1
The sofa-bed comprises at least a pair of tie rods made of elastomeric material
Implementation Method 2
The elastomeric tie rods significantly reduce the force required for opening and closing, provide a smooth and quiet operation
Data Source
AI summary
A sofa-bed includes a fixed frame and a foldable frame connected to the fixed frame and movable between an open configuration defining a bed configuration of the sofa-bed and a closed configuration defining a sofa configuration of the sofa-bed. The foldable frame includes levers hinged to the fixed frame.The sofa-bed includes at least a pair of tie rods made of elastomeric material, wherein each tie rod extends along a substantially longitudinal direction. A first end of each one of the tie rods is connected to fixed frame and a second end of each of the tie rods opposed with respect to the first end is associated to at least one of the levers.