Vibronic Measuring System Self-Diagnosis With Second-Mode Resonance
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Solution Overview
Problem
Vibronic measuring systems, such as Coriolis mass flow meters, suffer from reduced measuring accuracy and operational reliability due to wear, aging, and external loads, which can lead to irreversible changes in their vibration properties and system functions, potentially causing malfunctions and safety hazards.
Innovation Solution
A vibronic measuring system with improved design and positioning of the vibration exciter and sensors, along with advanced measuring system electronics, allows for early detection and signaling of malfunctions by utilizing specific vibration modes and modes for self-diagnosis, maintaining high accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the measuring system operates continuously under external loads, then productivity is improved, but reliability deteriorates due to wear and aging causing irreversible changes in vibration properties
Solution Approach 1:
The system performs preliminary self-diagnosis by exciting a second vibration mode and comparing its characteristics against reference values before catastrophic failure occurs. This early detection allows for maintenance scheduling that prevents both productivity loss and accuracy degradation.
Solution Approach 2:
The measuring system continuously monitors its own vibration properties through self-diagnosis, comparing current vibration mode characteristics against reference values. This feedback mechanism enables real-time detection of wear and aging effects, allowing corrective action before reliability deteriorates significantly.
2Reliability
If the system uses advanced self-diagnosis methods, then reliability is improved, but device complexity increases
Solution Approach 1:
The self-diagnosis function is activated periodically by providing a second excitation signal at a different frequency to excite a second vibration mode. This periodic action allows comprehensive monitoring without requiring continuous complex diagnostics, balancing reliability improvement with acceptable system complexity.
Solution Approach 2:
The system changes excitation parameters by switching between a first frequency (for normal operation) and a second frequency (for self-diagnosis). This parameter change enables the same hardware to perform both measurement and diagnostic functions, avoiding the need for separate complex diagnostic equipment.
3Measurement precision
If the vibration exciter is repositioned to reduce drive offset, then measurement precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The system uses different vibration modes for different purposes: the first vibration mode (with larger amplitude) is used for normal measurement operations, while the second vibration mode (with node at exciter position) is used specifically for self-diagnosis. This local quality approach allows each mode to be optimized for its specific function, reducing overall manufacturing precision requirements.
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 system effectively detects and signals malfunctions early, ensuring high measuring accuracy and operational reliability by minimizing deviations from reference states, thus preventing catastrophic failures and maintaining safety in industrial processes.
Implementation Method 1
an excitation arrangement for converting electrical power into mechanical power useful for exciting and maintaining forced mechanical vibrations of the pipe arrangement
Implementation Method 2
a sensor arrangement for detecting mechanical vibrations of the pipe arrangement and for providing vibration measurement signals representing vibrational movements of the pipe arrangement
Implementation Method 3
the pipe executes forced mechanical vibrations, for example bending vibrations, with one or more vibration frequencies predetermined by the driver signal
Implementation Method 4
each having a resonance frequency, in which the pipe can carry out or carries out vibration movements having one or more vibration antinodes and two or more vibration nodes
Data Source
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AI summary
The measuring system comprises a vibration-type transducer (10) and measuring system electronics (20), electrically coupled to the transducer (10), namely both to the exciter assembly thereof and to the sensor assembly thereof, for controlling the transducer and for evaluating vibration measurement signals provided by the transducer. The exciter assembly comprises a vibration exciter (31) which is designed to convert electrical power with an electrical current that changes over time into mechanical power, in such a way that, at a drive point, formed by the vibration exciter on the tube that is mechanically connected to the vibration exciter, a drive force that changes over time acts on the tube, wherein the vibration exciter (31) is positioned and designed such that a drive offset (ΔE), namely a smallest distance between a drive cross-sectional area of the tube surrounded by a notional circumferential line of the tube intersecting the drive point and a predefined reference cross-sectional area of the tube, is no more than 3°mm and/or less than 0.5% of the tube length, and wherein a vibration node of vibration movements formed between two vibration antinodes of said vibration movements of the at least one tube in a vibration mode of a second or higher order (deviating from a vibration mode of a first order) lies within the reference cross-sectional area. The measuring system electronics (20) is designed to feed electrical power into the vibration exciter (31) by means of an electrical drive signal (e1), having an electrical current that changes over time, in such a way that the tube performs forced mechanical vibrations with one or more vibration frequencies specified by the drive signal (e1), wherein the measuring system electronics is designed to both provide the drive signal (e1) at least periodically with a sinusoidal (second useful) current (eN2) having a (second) (alternating current) frequency, in such a way that the (alternating current) frequency deviates from a resonant frequency (f2) of a vibration mode of a second order naturally intrinsic to the tube by less than 1% of said resonant frequency (f2) and/or by less than 1 Hz, and also to carry out a (self) diagnosis of the measuring system based on a corresponding (second) useful signal component (s1N2; s2N2) of at least one of the vibration measurement signals (s1, s2).