Load Cell Overload Protection via Stop Element
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Solution Overview
Problem
Strain gauge load cells often sacrifice robustness and performance to minimize costs, making them susceptible to inaccuracies and malfunctions due to overloading, particularly when using materials like aluminum instead of more expensive stainless steel.
Innovation Solution
Incorporating a stop element with a bearing surface that engages the beam only above a threshold load, providing supplemental support to prevent yield conditions and damage during overloading, while maintaining efficient manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If aluminum material is used instead of stainless steel, then manufacturing cost is reduced, but robustness and resistance to overload damage deteriorate
Solution Approach 1:
The patent introduces a stop element positioned within a stop element channel that engages the beam before overload damage can occur. This pre-positioned protective mechanism cushions against excessive deflection and prevents yielding during overload conditions, allowing the use of lighter, cheaper materials like aluminum without sacrificing robustness
2Strength
If stop element is added to prevent overload damage, then robustness is improved, but device complexity increases
Solution Approach 1:
The load cell is segmented into functional zones: the beam for measurement, the stop element channel for protection, and the stop element for overload limitation. This segmentation allows the protective function to be added as a separate, modular component rather than integrating complexity into the beam structure itself
Solution Approach 2:
The stop element acts as an intermediary component between the beam and the overload condition. It mediates the interaction by engaging the beam at a predetermined position to limit deflection, protecting the beam from direct exposure to damaging overload forces without requiring complex active control systems
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
Enhances the robustness of strain gauge load cells by preventing yield conditions and malfunctions during overloading, reducing damage and replacement costs without significant additional manufacturing complexity or expense.
Implementation Method 1
strain gauge load cells measure the resistance variances of a strain gauge as a result of deformation of a material because of a load
Implementation Method 2
a stop element including a bearing surface coupled to the beam and configured such that the bearing surface does not engage the beam in a first position and engages the beam in a second position
Data Source
Figure 1~2B
Figure 2C~2D
Figure 3
AI summary
A load cell (200) that includes a beam (202) extending from a fixed section (204) to a load section (206) including a deflection section (208) that moves under a load and a central beam section (211) spaced from the deflection section (208). At least one strain gauge (216) is coupled to the beam (202) for detecting movement of the beam (202). Stop elements (234, 238, 242) each include a respective bearing surface (244, 246, 248) and are coupled to the beam (202) and configured such that each bearing surface (244, 246, 248) does not engage the beam (202) in a first position and engages the beam (202) in a second position.