Height Adjustable Bed Leg Assembly Spring Biasing
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Solution Overview
Problem
Height adjustable beds require greater motor power to initiate the raising sequence from a lowermost position due to the leg being tucked under the bed frame, resulting in a lack of effective angle and increased mechanical advantage.
Innovation Solution
A height adjustable patient support system incorporating motorized leg assemblies with a guide structure and non-motorized springs that provide longitudinal biasing force to assist in raising the bed from the lowermost position, allowing the actuators to operate with reduced power requirements and increased mechanical advantage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the leg is tucked under the bed frame at the lowermost position, then the bed structure is compact and stable, but the motor requires greater power to initiate raising due to lack of effective angle
Solution Approach 1:
The spring mechanism performs preliminary action by compressing during bed lowering to store energy, then releasing this energy during the initial raising phase to assist the motor. This preliminary energy storage and release resolves the contradiction by providing additional force when the motor needs it most, without compromising the stable tucked position.
Solution Approach 2:
The spring acts as a counterweight mechanism by providing an opposing force to the gravitational load during the initial raising phase. The compressed spring releases energy that counteracts the weight of the bed frame and patient, reducing the motor power required to overcome gravity when the leg is in the unfavorable tucked position.
2Reliability
If rigid mounting structures are used to secure springs to the patient support, then the spring mounting is secure, but the assembly becomes more difficult to service and replace
Solution Approach 1:
The mounting structure transitions from a static rigid connection to a dynamic removable connection. The improved mounting structure allows the spring to be securely mounted during operation but can be easily removed and replaced when needed, resolving the contradiction between secure mounting and ease of repair through conditional connectivity.
Solution Approach 2:
The mounting structure is segmented into separable components that can be independently assembled and disassembled. This segmentation allows the spring to be securely attached to the frame during operation while enabling easy removal and replacement of the spring assembly, balancing reliability with serviceability.
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 system reduces the initial motor power needed to raise the bed, improves force transfer, minimizes friction, and enhances the load lifting capability, enabling the safe handling of larger patients without excessive motor power.
Implementation Method 1
Spring members are mounted circumferentially on the linear guide rods. When the bed frame is in the lowermost position, the bearing blocks attached to the linear actuators longitudinally compress the springs between the bearing blocks and transverse cross-members of the bed frame. When the bed frame is sought to be raised the energy in the compressed springs act on the bearing blocks to assist the actuators during the first or initial movement along the linear guide rods.
Implementation Method 2
Patient support decks of height adjustable beds may be raised or lowered by way of actuators, for example linear actuators. The actuators may be motor driven and may be attached to pivoting legs and a bed frame
Data Source
AI summary
A height adjustable patient support has a frame, a pair of motor powered leg assemblies operable to vertically raise and lower the frame between a lowermost position and an uppermost position, a guide structure for longitudinally guiding an end of at least one of the pair of leg assemblies along the frame as the at least one of the pair of leg assemblies operates to vertically raise and lower the frame, and a non-motorized structure operable to longitudinally bias the end of the at least one of the pair of leg assemblies when the frame is in the lowermost position, the non-motorized structure mounted on the patient support by a mounting structure non-rigidly secured to the patient support. The non-motorized structure may assist with raising the frame from the lowermost position until motors operating the motor powered legs are able to continue with raising the frame.