Symmetrical Load Cell Assembly Mounting Effects

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Solution Overview

Problem

Existing load cell systems face inaccuracies due to 'loading and mounting effects' caused by shear forces and distortion, which are difficult to correct, especially in high-resolution applications, leading to compromised performance and increased costs.

Innovation Solution

A symmetrical load cell assembly with first and second mounting surfaces on the same horizontal plane, combined with a symmetrical load cell attachment bracket assembly, reduces mounting effects by using parallel-oriented brackets and strain gauges to detect shear forces and bending moments, enhancing accuracy and reducing material usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the load cell is stiffened to reduce shear and mounting effects, then measurement accuracy is improved, but material usage and manufacturing cost increase

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidmaterial usage
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent applies asymmetry by positioning the first and second mounting surfaces at different vertical locations on the load cell. This asymmetric arrangement allows the load cell to be less stiff overall (reducing material usage) while still controlling mounting effects through strategic placement of mounting surfaces rather than uniformly stiffening the entire structure.

Inventive Principle:
Principle #4Asymmetry

2Measurement precision

If the load cell is stiffened to reduce mounting effects, then measurement accuracy is improved, but manufacturing cost increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The asymmetric positioning of mounting surfaces at different vertical locations enables reduced material usage compared to traditional stiff-ended designs, directly lowering manufacturing costs while maintaining measurement accuracy through strategic geometry rather than excessive material.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The load cell structure is segmented into distinct functional regions with mounting surfaces positioned at specific locations rather than requiring uniform stiffness throughout. This segmentation allows material to be placed only where needed for mounting stability, reducing overall material usage and manufacturing cost.

Inventive Principle:
Principle #1Segmentation

3Measurement precision

If calibration is performed to compensate for loading and mounting effects, then measurement accuracy is improved, but the effects remain undetermined and unstable

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidstability of measurement
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The asymmetric mounting surface positioning reduces the magnitude of loading and mounting effects through geometric design, making them more deterministic and stable. This reduces reliance on calibration compensation and improves the inherent stability of measurements by minimizing the effects at the source rather than correcting them afterward.

Inventive Principle:
Principle #4Asymmetry

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 significantly reduces the impact of mounting effects, allowing for higher accuracy measurements, particularly in high-resolution applications, and eliminates the need for extensive calibration of individual load cells, thereby improving performance and reducing costs.

Implementation Method 1

strain gauges to detect shear forces and bending moments

Methodology Applied
Scientific EffectStrain gauge measurement: Piezoresistive Effect

Data Source

PatentEP2972140B1Load cell assembly
Publication Date: 2021.12.22 ILLINOIS TOOL WORKS INC
  • EP2972140B1 patent drawingFigure 1~5b
  • EP2972140B1 patent drawingFigure 6a~8(c)

AI summary

The invention relates to a load cell symmetrical about a central vertical axis and comprising first and second mounting surfaces, each on the same horizontal plane and configured for attachment to a support structure and to a loading fixture respectively.