Magnetic-Inductive Flowmeter Disturbance Compensation

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Solution Overview

Problem

Magnetic-inductive flow meters face challenges in maintaining high repeatability and accuracy due to indirect influences such as changes in the magnetic circuit device's properties, which can be caused by external magnetic fields, temperature variations, and mechanical vibrations, leading to increased production costs and larger, heavier devices.

Innovation Solution

Incorporating sensors on the magnetic circuit device to detect physical disturbance variables like temperature, external magnetic fields, and vibrations, with a control and evaluation device that signals or corrects for these influences, allowing for the detection and management of their effects on the flow measurement without the need for oversized or expensive designs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the magnetic circuit device is oversized and magnetic shielding is used to prevent saturation, then reliability is improved, but the device becomes heavier and larger

Engineering Contradiction:
Improveprevention of magnetic circuit saturationVSAvoidweight of magnetic circuit device
Core Design Contradiction:
ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent applies preliminary action by detecting physical disturbance variables (temperature, external magnetic fields, vibrations) before they cause saturation or significant measurement errors. Sensors monitor these variables continuously, and the control device compensates for their effects in advance or in real-time, preventing the need for oversized magnetic circuit components that would be required to withstand extreme conditions without compensation.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If high-quality materials with temperature-stable permeability are used, then measurement precision is improved, but production costs increase

Engineering Contradiction:
Improvestability of measuring magnetic fieldVSAvoidproduction cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent implements feedback by using sensors to detect physical disturbance variables (especially temperature) that affect the magnetic circuit device properties. The control and evaluation device receives this feedback information and actively compensates for the detected disturbances, adjusting measurements or operating parameters to maintain precision. This feedback mechanism allows the use of more economical materials while maintaining measurement stability through active compensation rather than relying solely on expensive temperature-stable materials.

Inventive Principle:
Principle #23Feedback

3Reliability

If the magnetic circuit device is overdimensioned to avoid saturation, then reliability is improved, but device complexity and size increase

Engineering Contradiction:
Improveresistance to external magnetic fieldsVSAvoidsize of magnetic circuit device
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses feedback control by detecting external magnetic fields and other physical disturbance variables with sensors mounted on the magnetic circuit device. The control device processes this information and compensates for the effects of detected disturbances, allowing the magnetic circuit device to be optimally sized rather than overdimensioned. This active compensation approach maintains reliability while reducing device size and complexity.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces the mechanical approach of preventing saturation through oversized magnetic circuit components with an electronic/control-based approach. Instead of mechanically designing the magnetic circuit to withstand all possible external fields, the system uses sensors to detect external magnetic fields and control electronics to compensate for their effects, substituting a control system for a purely mechanical solution.

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

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 approach enables a smaller, more economical flow meter design that can detect and manage disturbances, ensuring reliable flow measurements by signaling when limits are exceeded or correcting for their effects, thus maintaining measurement accuracy without the need for complex or costly designs.

Implementation Method 1

a magnetic field generating device (3) for generating a measuring magnetic field that penetrates the measuring tube (2)... Due to the flow of the medium in the measuring tube, an induction voltage is induced in the medium by charge separation

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a magnetic circuit device (4) for guiding the measuring magnetic field outside the measuring tube (2)... which is usually made of a soft magnetic material

Methodology Applied
Scientific EffectMagnetic flux guidance: Magnetic Field

Data Source

PatentEP3415875B1Magnetic-inductive flow measuring device and method for operating a magnetic-inductive flow measuring device
Publication Date: 2022.03.16 KROHNE MESSTECHNICK GMBH & CO KG
  • EP3415875B1 patent drawingFigure 1
  • EP3415875B1 patent drawingFigure 2
  • EP3415875B1 patent drawingFigure 3

AI summary

The invention relates to a magnetic-inductive flowmeter (1) for measuring the flow rate of a conductive medium, comprising a measuring tube (2), a magnetic field generation device (3) for generating a measuring magnetic field passing through the measuring tube (2), a magnetic circuit device (4) for guiding the measuring magnetic field outside the measuring tube (2), electrodes (5) for detecting a flow-dependent electrical measuring voltage when the conductive medium flows through the measuring tube (2), and an electronic control and evaluation device (6).The problem of providing a magnetic-inductive flowmeter (1) that has a smaller and more cost-effective design than magnetic-inductive flowmeters known from the prior art is solved by arranging a sensor (7) on the magnetic circuit device (4) for detecting a physical disturbance acting on the magnetic circuit device (4), wherein the measuring magnetic field is influenced by the physical disturbance, and wherein the control and evaluation unit (6) is designed such that it detects and signals when a predefinable limit value of the physical disturbance is exceeded or fallen below, and/or corrects the effect of the physical disturbance on the flow measurement. The invention also relates to a method for operating a magnetic-inductive flowmeter (1).