Load Cell Swing Link Assembly for Accurate Bariatric Bed Weighing
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Solution Overview
Problem
Conventional bariatric patient support apparatuses experience deformation of the load cell interface during loading and unloading, leading to inaccurate weight scale readings due to high contact forces.
Innovation Solution
A patient support apparatus with a load cell assembly that includes a swing link mechanism between the first and second frame assemblies, allowing the second frame assembly to move relative to the first frame assembly along both longitudinal and transverse axes, thereby reducing friction and ensuring accurate weight measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rigid load cell interface is used in conventional bariatric patient support apparatuses, then the structure is simple and strong, but high contact forces during loading and unloading cause deformation of the load cell interface leading to inaccurate load scale readings
Solution Approach 1:
The patent applies the dynamics principle by introducing a swing link mechanism that allows the load cell interface to move dynamically between fixed and movable states. The swing link pivots to accommodate movement of the patient support deck while maintaining accurate load measurements, preventing deformation of the load cell interface during loading and unloading operations.
Solution Approach 2:
The swing link acts as an intermediary element between the load cell and the patient support deck. It mediates the interaction by allowing relative movement while transmitting accurate force measurements, thereby protecting the load cell interface from direct contact forces that would cause deformation.
2Reliability
If the load cell interface is made more robust to withstand high contact forces, then the durability improves, but the manufacturing precision and alignment become more difficult to maintain
Solution Approach 1:
The swing link mechanism provides dynamic adjustment capability that compensates for manufacturing tolerances and alignment variations. By allowing the interface to move within certain limits while maintaining the pivot relationship, the system achieves both durability and manufacturing precision without requiring extremely tight tolerances on rigid components.
3Measurement precision
If a fixed rigid connection is used between the load cell and frame assemblies, then the structural stability is high, but friction builds up during repeated movement causing inaccurate measurements
Solution Approach 1:
The swing link provides a dynamic pivot connection that eliminates static friction buildup. The pivoting motion allows the load cell interface to move smoothly with the patient support deck while maintaining accurate force transmission, preventing the friction problems associated with fixed rigid connections.
Solution Approach 2:
The swing link mechanism undergoes periodic pivoting movements during normal operation, which prevents friction from accumulating. The repeated small angular movements keep the interface active and prevent sticking, ensuring consistent accurate measurements throughout the service life of the apparatus.
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 swing link mechanism ensures consistent and reliable weight measurements by minimizing friction and accommodating manufacturing tolerances, preventing damage to load cell components, and maintaining accurate scale readings.
Implementation Method 1
The swing link is arranged for pivoting movement relative to the first pivot mount and arranged for pivoting movement relative to the second pivot mount such that the second frame assembly is movable with respect to the first frame assembly in a direction following the longitudinal axis and in a direction following the transverse axis
Data Source
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AI summary
A patient support apparatus comprises a patient support deck and a base frame assembly. The base frame assembly comprises a first frame assembly supporting a plurality of wheels, and a second frame assembly supporting one or more lift arms that are coupled to the patient support deck to the second frame assembly. A load cell assembly is interposed between the first and second frame assemblies to sense force acting on the first frame assembly associated with weight applied to the second frame assembly. The load cell assembly comprises: a load cell element coupled to one of the first frame assembly and the second frame assembly; a first pivot mount operatively attached to the load cell element; a second pivot mount operatively attached to the other of the first frame assembly and the second frame assembly; and a swing link arranged for pivoting movement.