Jack Piston Strain Gauge Load Measurement

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Solution Overview

Problem

Existing methods for measuring the load applied by hydraulic jacks are temperature-sensitive and do not accurately account for frictional forces, leading to inaccuracies in load calculations.

Innovation Solution

Incorporating strain gauges into the piston of a jack to measure deformation and displacement caused by applied loads, allowing for precise calculation of the load using the relationship Load = ε AE / L, where ε is strain, A is the contact area, E is the elastic modulus, and L is the length of the material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If pressure-based measurement method is used, then measurement simplicity is improved, but measurement precision deteriorates due to temperature sensitivity and friction

Engineering Contradiction:
Improvemeasurement simplicityVSAvoidload calculation accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent replaces the traditional pressure-based measurement system with a strain gauge-based measurement system. Instead of using pressure sensors to measure hydraulic fluid pressure and calculate load, the invention directly measures mechanical strain in the piston rod using strain gauges. This substitution eliminates the temperature sensitivity and friction issues inherent in pressure-based methods, providing more accurate load measurements while maintaining operational simplicity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces strain gauges as an intermediary measurement element between the mechanical load and the measurement system. The strain gauges are bonded to the piston rod and convert mechanical strain into electrical signals that can be measured and processed. This intermediary approach allows direct measurement of the actual load applied by the jack, bypassing the indirect pressure-based calculation method that suffers from temperature and friction errors.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If strain gauges are incorporated into the piston, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improveload measurement accuracyVSAvoidjack structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the measurement function directly into the existing piston rod structure by bonding strain gauges to its surface. Rather than adding a separate measurement device or subsystem, the strain gauges are integrated with the structural component that already experiences the load. This merging approach minimizes additional complexity while achieving precise load measurement through direct strain measurement of the piston rod.

Inventive Principle:
Principle #5Merging (Combining)

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 method provides accurate and temperature-independent load measurements by directly measuring strain, accounting for frictional forces and improving the precision of load calculations compared to traditional pressure-based methods.

Implementation Method 1

one or more strain gauges, additional to the one or more strain gauge of the invention, are positioned on, within, or integral with one or more materials of the jack. When a load or force is applied by the jack, the one or more materials within the jack are deformed or displaced as a result of the applied load. The one or more strain gauges are used to measure the deformation or displacement and thus measure the strain.

Methodology Applied
Scientific EffectStrain measurement: Deformation

Implementation Method 2

When a hydraulic jack is used, it is known to measure the pressure of hydraulic fluid in the hydraulic jack and to use such measure of the pressure of the hydraulic fluid and the surface area of the jack effectively normal to the direction of the force in contact with the hydraulic fluid to calculate the load applied by the hydraulic jack. The load is typically the pressure of the hydraulic fluid times the surface area effectively normal to the direction of force being applied by the hydraulic fluid.

Methodology Applied
Scientific EffectHydraulic pressure: Pressure Increase

Data Source

PatentEP2572174B1Method and apparatus for internally determining a load applied by a jack
Publication Date: 2018.02.21 LOADTEST INC
  • EP2572174B1 patent drawingFigure 1A~1B
  • EP2572174B1 patent drawingFigure 2
  • EP2572174B1 patent drawingFigure 3A~3C

AI summary

An embodiment of the subject invention is directed to a jack incorporating one or more strain gauges. The one or more strain gauges can be positioned on, within, or integral to the jack. When a load or force is applied by the jack, one or more materials within the jack are deformed or displaced as a result of the applied load. The one or more strain gauges are used to measure the deformation or displacement and thus measure the strain. The measured strain can be used to determine the magnitude of the load applied by the jack. In an embodiment, a plurality of strain gauges are used and the resulting strain measurements can be combined to determine the applied load.