Pivot Lever with Variable Lever Arm for Adjustable Bed Support Frames
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Solution Overview
Problem
Existing electromotively adjustable support apparatuses for seating and reclining furniture, such as slatted frames, face challenges in applying sufficient adjustment forces, especially when dealing with mattresses that deform elastically, like box spring mattresses, as the restoring forces increase at the end of the adjustment movement, requiring higher forces to overcome these forces under load conditions.
Innovation Solution
The design incorporates a pivot lever that is pivotable under the traction effect of a Bowden cable, with a changing lever arm length between the unadjusted and maximally adjusted positions, allowing for increased adjustment force at the end of the movement, which is achieved by shaping the pivot lever as a curved body or guiding the pull cable around a curved body connected to the pivot lever, ensuring a desired course of adjustment force during the movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional spindle drive or cable-pulley system is used for adjusting support parts, then the structure is relatively simple and easy to manufacture, but the adjustment force decreases at the end of the adjustment movement, making it insufficient to overcome the increasing restoring forces of elastic mattresses
Solution Approach 1:
The pivot lever is designed with a curved geometry instead of a straight shape. This curvature causes the lever arm length to change dynamically during the adjustment movement, automatically increasing the adjustment force when the support part approaches the maximally adjusted position, thereby overcoming the restoring forces of elastic mattresses without requiring complex additional mechanisms
Solution Approach 2:
The invention changes the geometric parameter of the pivot lever (its shape from straight to curved) to achieve dynamic variation in the lever arm length during operation. This parameter change enables the adjustment force to vary throughout the movement range, providing higher force at the end position where it is most needed
2Force
If the lever arm length is kept constant throughout the adjustment movement, then the device structure is simpler, but the adjustment force remains constant and insufficient to overcome increasing restoring forces at the end of movement
Solution Approach 1:
The pivot lever is designed with a curved geometry instead of a straight shape. This curvature causes the lever arm length to change dynamically during the adjustment movement, automatically increasing the adjustment force when the support part approaches the maximally adjusted position, thereby overcoming the restoring forces of elastic mattresses without requiring complex additional mechanisms
Solution Approach 2:
The invention transitions from a static lever arm length to a dynamic one that changes during operation. The curved pivot lever ensures that the lever arm length is not fixed but varies continuously throughout the adjustment movement, adapting the adjustment force to the instantaneous mechanical conditions and providing higher force when needed
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
This configuration enables the application of larger adjustment forces at the maximally adjusted end position, even under the load of a person, effectively overcoming the restoring forces of elastic mattresses, ensuring smooth and complete adjustment of support parts.
Implementation Method 1
a pivot lever (102) which is pivotable under the traction effect of a pull cable (110) of a Bowden cable
Data Source
AI summary
Electromotively adjustable support apparatus for supporting padding of seating and/or reclining furniture, in particular a mattress of a bed, has at least two support parts adjustable relative to one another. The adjustable support apparatus may be adjusted by an electric motor. An adjustment element is associated with one support part for adjusting the support part. Adjustment element is in drive connection with an electric motor of a drive unit. The adjustment element is a pivot lever which is pivotable under the traction effect of a pull cable of a Bowden cable, and is configured and connected with the pull cable in such a way that the lever arm which is operative for adjusting the support part lengthens during an adjustment from an unadjusted starting position into a maximally adjusted end position of the adjustment movement.