Coriolis Flowmeter Magnetic Field Detector
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Solution Overview
Problem
Conventional Coriolis mass flowmeters face significant measurement errors due to external magnetic fields, which can lead to inaccurate mass flow measurements, despite efforts to reduce these errors using materials with high magnetic conductivity and slits in magnet cups to suppress eddy currents.
Innovation Solution
A Coriolis mass flowmeter design that includes a magnetic field detector, such as a Hall-sensor or reed switch, to detect external magnetic fields and quantify their influence, allowing the transmitter circuit to assess whether an external magnetic field is present and adjust measurements accordingly, thereby minimizing its impact on measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional Coriolis mass flowmeters are used without magnetic field detection, then the device structure remains simple, but measurement accuracy deteriorates due to external magnetic field interference
Solution Approach 1:
A magnetic field detector is introduced as an intermediary component between the external magnetic field and the oscillation sensors. This detector monitors the magnetic field environment and provides information to the transmitter circuit, which then compensates for magnetic field effects on the mass flow measurement, thereby maintaining accuracy without requiring the entire system to be magnetically shielded
Solution Approach 2:
The magnetic field detector provides feedback information about the external magnetic field conditions to the transmitter circuit. Based on this feedback, the transmitter circuit adjusts the measurement evaluation to compensate for magnetic field influences, creating a closed-loop system that maintains measurement accuracy despite external interference
2Object-affected harmful factors
If magnetic shielding materials with high magnetic conductivity are used, then external magnetic field influence is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
Instead of using magnetic shielding materials as an intermediary to block the magnetic field, the patent introduces a magnetic field detector as an intermediary that monitors and communicates magnetic field conditions to the evaluation circuit, which then compensates for the effects digitally or through signal processing
Solution Approach 2:
The patent replaces the mechanical/physical approach of magnetic shielding with materials with the electronic/software-based approach of magnetic field detection and compensation through the transmitter circuit, thereby avoiding the need for complex magnetically conductive housing materials
3Measurement precision
If slits are added to magnet cups to suppress eddy currents, then measurement accuracy improves, but manufacturing complexity increases
Solution Approach 1:
Rather than modifying the magnet cup structure with slits to suppress eddy currents, the patent introduces a magnetic field detector as an intermediary that monitors external magnetic fields and enables compensation through the transmitter circuit, avoiding the need for complex magnet cup manufacturing
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
The integration of a magnetic field detector enables timely detection and reporting of external magnetic field influences, reducing measurement errors and maintaining the integrity of mass flow measurements by distinguishing between internal and external magnetic fields.
Implementation Method 1
a magnetic field detector, such as a Hall-sensor or reed switch, to detect external magnetic fields
Implementation Method 2
at least a first magnetic field detector (61) for registering a magnetic field (H0+H1) originating at least partially outside of the oscillation sensors (51, 52)
Implementation Method 3
an electrodynamic, first oscillation sensor (51) and at least an electrodynamic, second oscillation sensor (52)... the first oscillation sensor (51) is adapted to convert oscillatory movements of the at least one vibration element (10) into an electrical, first oscillation measurement signal (s1)
Data Source
AI summary
The Coriolis mass flowmeter comprises a measuring transducer having a vibration element, an exciter arrangement, and a sensor arrangement The flowmeter further includes an electronic transmitter circuit coupled with the exciter arrangement and the sensor arrangement. The transmitter circuit supplies power to the exciter arrangement to force mechanical oscillations having a wanted frequency. The sensor arrangement includes two electrodynamic oscillation sensors to convert oscillatory movements of the vibration element into an electrical signal having an alternating voltage having an amplitude dependent on the wanted frequency and on a magnetic flux of its oscillation sensor. The sensor arrangement includes a magnetic field detector adapted to convert changes of the magnetic field into a magnetic field signal having an amplitude dependent on a magnetic flux and/or an areal density of the magnetic flux. The transmitter circuit ascertains mass flow measured values and ascertains whether an external magnetic field is present.