Force Measuring Device with Sealed Strain Gauges

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Solution Overview

Problem

Existing force measurement devices are ineffective in accurately measuring forces that are not parallel to the longitudinal axis and are vulnerable to contamination, leading to inaccurate readings and potential accidents in harsh environments, particularly in crane systems.

Innovation Solution

The design features precisely aligned support plates with measuring points between them, allowing for direct force component transmission and encapsulation with a sealing sleeve to protect strain gauges from environmental damage, enabling reliable force measurement even in contaminated and acidic conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If measuring points are offset laterally to the pairs of supports, then the base body structure is simplified, but the measurement precision deteriorates because the measuring points are not directly in the flow of forces

Engineering Contradiction:
Improvebase body structureVSAvoidforce measurement accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The base body is divided into multiple measuring points, each equipped with strain gauges that measure different force components. This segmentation allows the system to capture both axial and lateral force components separately, maintaining measurement precision while simplifying the overall structure by distributing measurement functions across multiple locations rather than requiring a complex single-point measurement system.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If the wall thickness of the ring-shaped base body is designed to be relatively small, then the device complexity is reduced, but the strength deteriorates because only small torsional forces can be supported

Engineering Contradiction:
Improvebase body designVSAvoidtorsional force capacity
Core Design Contradiction:
Device complexityVSStrength

Solution Approach 1:

The base body utilizes composite structural design combining the ring-shaped geometry with strategically placed reinforcing elements. This allows the maintenance of a relatively thin overall wall thickness for simplified manufacturing while incorporating localized reinforcement at critical stress points to maintain adequate torsional strength.

Inventive Principle:
Principle #40Composite materials

3Manufacturing precision

If strain gauges are glued directly to the measuring point, then the manufacturing precision is improved, but the reliability deteriorates in contaminated environments because the adhesive layer can be destroyed by moisture ingress

Engineering Contradiction:
Improvestrain gauge attachmentVSAvoidmeasurement reliability in harsh environments
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

A protective coating or encapsulation layer is introduced as an intermediary between the strain gauges and the harsh external environment. This intermediate layer protects the adhesive bond from moisture and contamination while allowing the strain gauges to remain directly attached to the measuring point, thus maintaining both manufacturing simplicity and reliability in harsh environments.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Adaptability or versatility

If the measuring device is used in contaminated environments, then the adaptability is improved, but the measurement precision deteriorates because contamination deflects the introduction of force

Engineering Contradiction:
Improveenvironmental adaptabilityVSAvoidforce measurement accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The measuring device incorporates multiple measuring points with strain gauges oriented in different directions, enabling it to measure various force components (axial, lateral, torsional) simultaneously. This multi-functional capability allows the device to accurately measure forces even when their direction is altered by contamination or bending, maintaining measurement precision across diverse operational conditions.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 design ensures accurate measurement of total forces, including those at angles, and protects the strain gauges from environmental harm, preventing overloading and damage to lifting devices in harsh environments.

Implementation Method 1

The strain gauges are attached to the inner lateral surface of the base body at the measuring point

Methodology Applied
Scientific EffectStrain gauge measurement: Piezoresistive Effect

Data Source

PatentEP2251661B1Force measuring device
Publication Date: 2013.01.02 BROSA AG
  • EP2251661B1 patent drawingFigure 1
  • EP2251661B1 patent drawingFigure 2~3a
  • EP2251661B1 patent drawingFigure 3b

AI summary

The device (1) has supporting plates (7, 8) running parallel to each other, where a rubber seal is utilized in one of the plates (8). The plates are attached at a base body (2), and supporters (11) are arranged at the plates. A geometrical middle point of the supporters run on a common force transmission axis, which is parallel to a longitudinal axis (3) of the base body. Strain gauges (6) of a measuring point (12) are arranged at the force transmission axis in a lateral displaced or aligned manner, and designed as an optical strain gauges or foil or thin film measuring strips.