Sofa Bed Kinematic Chain With Single-Actuator Opening
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Solution Overview
Problem
Existing sofa bed mechanisms require multiple actuators and complex constructions, leading to economic and reliability issues, as well as safety concerns due to unpredictable movements and intense stresses on the mechanism, especially when converting between sofa and bed configurations.
Innovation Solution
A sofa bed design utilizing a single linear actuator with a kinematic chain of interconnected levers, allowing for automatic conversion between configurations with reduced force requirements and improved reliability, where the actuator is positioned within the fixed framework to minimize stress and enhance safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple actuators are used to enable automatic conversion between sofa and bed configurations, then the ease of operation is improved, but the device complexity and cost increase
Solution Approach 1:
The patent combines multiple actuation functions into a single linear actuator that controls the entire conversion mechanism through a series of interconnected levers. This single actuator replaces what would traditionally require multiple actuators, thereby reducing device complexity while maintaining automatic conversion capability. The lever system distributes the actuation force appropriately across different movement stages.
Solution Approach 2:
The patent introduces a series of levers as intermediary mechanical elements between the single linear actuator and the movable frames. These levers act as mediators that translate the linear actuator's motion into the complex multi-stage movement required for conversion, enabling one actuator to control what would otherwise require multiple direct actuators.
2Productivity
If the actuator is positioned to provide sufficient force for conversion, then the productivity is improved, but the stress on the mechanism and safety concerns increase
Solution Approach 1:
The patent employs a dynamic lever system that adapts the mechanical advantage at different stages of the conversion process. The levers are positioned and dimensioned to provide optimal force multiplication when needed while maintaining controlled motion throughout the conversion, thereby achieving productive conversion speed without subjecting the mechanism to excessive stress.
Solution Approach 2:
The conversion mechanism is segmented into multiple movement stages controlled by the lever system. Each lever stage handles a specific portion of the conversion process, distributing the overall force requirements across multiple controlled movements rather than requiring one high-stress movement, thus maintaining productivity while reducing peak stress on any single mechanism component.
Data Source
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AI summary
A sofa bed (1a, 1b) with facilitated opening, particularly with automatic actuation, comprising a fixed framework (2) which defines a compartment (7) for accommodating a mattress (8) that can fold into at least four parts and is supported by at least four movable frames (9, 10, 11, 12), one for each one of the parts of the mattress (8), the first movable frame (9) being associated with the fixed framework (2); the four movable frames (9, 10, 11, 12) are mutually articulated sequentially with respect to each other to define a kinematic chain, with one degree of freedom, which can move between a closed configuration, in which the four movable frames (9, 10, 11, 12) are substantially mutually opposite in pairs so as to define a cagelike structure that encloses the mattress (8) folded into at least four parts, and an open configuration, in which the four movable frames (9, 10, 11, 12) are substantially mutually aligned to define a resting surface on which the unfolded mattress (8) lies.