Coriolis Sensor Coil Winding for Magnetic Interference Cancellation

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Solution Overview

Problem

Coriolis measuring devices are susceptible to manipulation and measurement distortion due to external magnetic fields, causing interference with magnetic coupling and eddy currents that affect the accuracy of mass flow and density measurements.

Innovation Solution

A Coriolis sensor system with a specific configuration of measuring tubes, sensors, and coils, where the coils are connected in series with opposite winding directions to cancel out interference voltages induced by external magnetic fields, while allowing measurement voltages from permanent magnets to be additive and accurate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If magnetic coupling sensors are used in Coriolis measuring devices, then the sensors can detect measuring tube vibrations, but the devices become susceptible to manipulation and measurement distortion by external magnetic fields

Engineering Contradiction:

Improvevibration detection capabilityVSAvoidexternal magnetic field interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of external magnetic fields into a beneficial cancellation mechanism. By arranging coils with opposite winding directions and connecting them in series, the interference voltages induced by external magnetic fields in both coils are made to have opposite polarities, causing them to cancel each other out. This transforms the harmful magnetic field interference into a self-neutralizing effect, while the measurement signal from the permanent magnet is preserved through differential evaluation of the sensor signals.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Measurement precision

If coils are used to detect measuring tube vibrations, then vibration detection is achieved, but eddy currents are induced in the measuring tube walls that distort the measurement signal

Engineering Contradiction:

Improvevibration signal detectionVSAvoideddy currents in measuring tube walls

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent addresses eddy current interference by using the opposite winding direction configuration to induce opposite polarity voltages in the two coils. The eddy current-induced voltages, being identical in nature for both coils, are converted into canceling signals through the series connection with opposite windings, transforming the harmful distortion into a beneficial cancellation effect.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Adaptability or versatility

If external magnets are used to manipulate or interfere with the sensor, then manipulation becomes possible, but the magnetic coupling is disturbed causing measurement errors

Engineering Contradiction:

Improvesensor operation in magnetic environmentsVSAvoidmeasurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent enables reliable operation in magnetic environments by configuring the coils with opposite winding directions and connecting them in series. This configuration causes interference voltages from external magnets to cancel out, while the measurement signal from the permanent magnet attached to the measuring tube is preserved through differential evaluation, thus converting potential manipulation vulnerabilities into robust measurement capability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

Significantly reduces zero point errors by more than a factor of 10 compared to traditional Coriolis sensors, ensuring accurate mass flow and density measurements even in the presence of external magnetic fields.

Implementation Method 1

the at least one permanent magnet is configured to generate, in the region of the coils, an inhomogeneous magnetic field having a field component perpendicular to the cross-sectional surfaces of the coils

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

at least one magnet device is configured to be moved relative to at least one coil device by measuring tube vibrations

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

an external magnetic field causes, on the one hand, an alternating voltage directly in the coils moved with the measuring tube and, on the other hand, eddy currents, for example in walls of the measuring tube, which eddy currents distort a measurement signal detected by means of the coils

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Data Source

PatentUS11841258B2Coriolis measuring sensor and coriolis measuring device having a coriolis measuring sensor

Publication Date: 2023.12.12 ENDRESS HAUSER FLOWTEC AG

AI summary

A Coriolis measuring sensor of a Coriolis measuring device includes: at least a pair of measuring tubes; a support body; at least one exciter; and at least two electromagnetic sensors per pair of measuring tubes, wherein the electromagnetic sensors are configured to mask interference magnetic fields and to detect local inhomogeneous magnetic fields generated by magnet devices of the sensor according to a winding direction and/or an interconnection configuration of coils of the magnet devices.