Magnetic-inductive flow meter with permanent magnets
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Solution Overview
Problem
Magnetic-inductive flow meters have high power consumption due to constant operation of coil systems generating alternating magnetic fields, which is a challenge especially for battery-operated and two-wire field devices.
Innovation Solution
Incorporating a pair of permanent magnets to generate a permanent magnetic field that induces a measuring voltage when the alternating magnetic field is switched off, allowing for intermittent activation of the coil system only when flow changes are detected, thereby reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the coil system is operated continuously to generate alternating magnetic field for flow measurement, then the measurement precision is improved, but the power consumption increases
Solution Approach 1:
The coil system is activated periodically rather than continuously. The control unit switches the coil system on only when a change in flow is detected by the permanent magnets, and keeps it off during stable flow conditions. This periodic activation maintains measurement capability while dramatically reducing average power consumption.
Solution Approach 2:
The permanent magnets continuously monitor the flow in advance, detecting changes before they require precise measurement. This preliminary detection allows the system to activate the power-consuming coil system only when necessary, rather than running it continuously for all measurement conditions.
2Use of energy by moving object
If the coil system is switched off to reduce power consumption, then the power consumption is reduced, but the flow monitoring capability is lost
Solution Approach 1:
The permanent magnets serve as an intermediary monitoring system that continuously tracks flow changes without requiring the alternating magnetic field. They detect flow variations and trigger the coil system only when changes occur, maintaining reliability while enabling power savings during stable conditions.
Solution Approach 2:
The system uses feedback from the permanent magnets' continuous flow detection to control the coil system activation. When the permanent magnets detect a flow change, they provide feedback to the control unit to activate the coil system for precise measurement, ensuring the system responds reliably to actual flow conditions.
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 the average power consumption of the flow meter while maintaining precise flow monitoring and measurement capabilities.
Implementation Method 1
Charge carriers in the medium moving perpendicularly to a magnetic field induce a measuring voltage in measuring electrodes arranged essentially perpendicularly to the flow direction of the medium and perpendicularly to the direction of the magnetic field. The measuring voltage induced in the measuring electrodes is proportional to the mean flow velocity of the medium over the cross section of the measuring tube
Implementation Method 2
An alternating magnetic field is usually used, which is generated by means of a coil system. The measuring voltage induced in the measuring electrodes is proportional to the mean flow velocity of the medium over the cross section of the measuring tube
Data Source
Figure 1A
Figure 1B~1C
Figure 2A~2B
AI summary
The invention relates to a magnetically inductive through-flow measuring device for measuring the through-flow of a flowable medium. The through-flow measuring device comprises a measuring tube, a pair of coils which are arranged opposite one another on the measuring tube, and which are designed to generate an activatable and deactivatable magnetic alternating field that is directed substantially in a transverse direction in relation to the longitudinal axis of the measuring tube, as well as comprising a pair of permanent magnets which are arranged opposite one another on the measuring tube, and which are designed to generate a permanent magnetic field that is directed substantially in a transverse direction in relation to the longitudinal axis of the measuring tube. In addition, the through-flow measuring device comprises one or more pairs of measuring electrodes arranged opposite one another on the measuring tube, of which a pair of measuring electrodes is designed to tap a measuring voltage induced via the permanent magnetic field when the magnetic alternating field is deactivated, and an evaluation unit that is designed, in the event that the magnetic alternating field is deactivated, to monitor the measuring voltage induced via the permanent magnetic field, to activate the magnetic alternating field at least in the event of a predefined change of the measuring voltage, and to determine a measured value for the through-flow by means of the magnetic alternating field.