| CPC G01F 1/8431 (2013.01) [G01F 1/8413 (2013.01); G01F 1/849 (2013.01)] | 55 Claims |
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1. A vibronic measuring system, including a Coriolis mass flow measuring device or Coriolis mass flow/density measuring device, for measuring and/or monitoring at least one measured variable, including at least one of a mass flow, a volumetric flow, and a flow rate, and/or a substance parameter, including a density and/or a viscosity, of a fluid measured substance, including a gas, a liquid, or a dispersion, which measuring system, which is configured as an in-line measuring device and/or a measuring device of compact design, the measuring system comprising:
a transducer including a tube assembly configured to conduct the measured substance flowing therethrough, an exciter assembly configured to convert electrical power into mechanical power suitable to excite and maintain forced mechanical vibrations of the tube assembly, and a sensor assembly configured to detect mechanical vibrations of the tube assembly and to generate vibration measurement signals respectively representing vibration movements of the tube assembly; and
an electronics unit, which is electrically coupled to both the exciter assembly and the sensor assembly by electrical connecting lines, the electronics unit, including at least one microprocessor, configured to control the transducer and to evaluate the vibration measurement signals generated by the transducer,
wherein the tube assembly includes at least one tube, which is at least sectionally curved and/or at least sectionally straight and which includes a first tube,
wherein the first tube extends from a first first tube end to a second first tube end with a tube length of more than 100 mm, and includes a lumen enclosed by a first tube wall, which extends from the first first tube end to the second first tube end,
wherein the first tube of the at least one tube is configured to be traversed by the measured substance at least in a flow direction from the first first tube end to the second first tube end while being allowed to vibrate, and wherein, inherent in the at least one tube, is a plurality of vibration modes, which are natural vibration forms, respectively having an associated resonance frequency, in which vibration modes the at least one tube can perform or performs vibration movements respectively having one or more vibration antinodes and two or more vibration nodes, such that:
vibration movements of the at least one tube in a fundamental vibration mode, which is a first-order vibration mode, include exactly one vibration antinode and two vibration nodes; and
vibration movements of the at least one tube in a harmonic mode, which is a second-order or higher-order vibration mode, include two or more vibration antinodes and three or more vibration nodes,
wherein the exciter assembly includes an electrodynamic vibration exciter mechanically connected to the at least one tube and configured to convert electrical power with a temporally variable electrical current into mechanical power such that, at a drive point formed by the vibration exciter on the at least one tube mechanically connected thereto, a temporally variable drive force acts on the at least one tube such that a line of action of the drive force is perpendicular to a normal of a drive cross-sectional area of the at least one tube,
wherein the vibration exciter is positioned and aligned such that a drive offset, which is a smallest distance between the drive cross-sectional area of the at least one tube enclosed by an imaginary circumferential line of the at least one tube passing through the drive point and a specified reference cross-sectional area of the at least one tube, which is determined using an intact or new transducer, is not more than 3 mm and/or less than 0.5% of the tube length, wherein a vibration node formed between two vibration antinodes of the vibration movements of the at least one tube in a second-order or higher-order vibration mode deviating from the first-order vibration mode and nominally located at half the tube length, is within the reference cross-sectional area, and wherein the drive offset of the intact or new transducer is substantially zero,
wherein the electronics unit is configured to energize the vibration exciter with electrical power via an electrical drive signal having a temporally variable electrical current such that the at least one tube performs forced mechanical vibrations at one or more vibration frequencies specified by the drive signal,
wherein the sensor assembly includes an electrodynamic or optical first vibration sensor, which is positioned on and at least partially mechanically connected to the first tube at a distance from the vibration exciter in the flow direction of more than 10 mm and/or more than one fifth of the tube length, the first vibration sensor configured to detect vibration movements of the first tube and convert said vibration movements into an electrical or optical first vibration measurement signal representing said vibration movements such that the first vibration measurement signal contains one or more sinusoidal signal components respectively having a frequency corresponding to a vibration frequency of vibration movements of the first tube,
wherein the sensor assembly includes at least one electrodynamic or optical second vibration sensor, which is positioned on and at least partially mechanically connected to the first tube at a distance from the vibration exciter in the flow direction of more than 10 mm and/or more than one fifth of the tube length and/or at a distance from the first vibration sensor in the flow direction, the second vibration sensor configured to detect vibration movements of the first tube and convert said vibration movements into an electrical or optical second vibration measurement signal representing said vibration movements such that the second vibration measurement signal contains one or more sinusoidal signal components respectively having a frequency corresponding to a vibration frequency of vibration movements of the first tube,
wherein the electronics unit is configured to:
receive and evaluate the first and second vibration measurement signals, including to determine and output measured values representing the at least one measured variable;
provide the drive signal at least intermittently with a sinusoidal first current having a first frequency such that:
the first tube performs first useful vibrations, which are mechanical vibrations forced by the vibration exciter, at a first useful frequency, which is a vibration frequency corresponding to the first frequency of the drive signal; and
the first useful frequency deviates from a resonance frequency of the fundamental vibration mode by less than 1% of said first resonance frequency and/or by less than 1 Hz; and/or
the first useful frequency deviates from a resonance frequency of the second-order vibration mode by more than 5% of said resonance frequency and/or by more than 10 Hz; and/or
the first useful vibrations are suitable for causing Coriolis forces in the flowing measured substance that depend upon the mass flow; and
each of the first and second vibration signals respectively includes a first useful signal component, which is a sinusoidal signal component having a signal frequency corresponding to the first useful frequency;
determine, based upon at least the signal frequency and/or signal amplitude of at least one of the first useful signal components, and/or based upon a phase angle of at least one of the first useful signal components, measured values representing the at least one measured variable, including mass-flow measured values representing the mass flow of the measured substance and/or density measured values representing the density of the measured substance; and
provide the drive signal during a test interval that lasts no less than 1 second(s) and/or is time-limited and/or recurrently started, with a sinusoidal second current having a second frequency such that:
the second AC frequency, for two or more vibration periods and/or a period of more than 10 ms (milliseconds), deviates from the resonance frequency of the second-order vibration mode by less than 1% of said resonance frequency and/or by less than 1 Hz;
the first tube performs, simultaneously with the first useful vibrations and/or stationarily for two or more vibration periods and/or a period of more than 10 ms, second useful vibrations having a constant, non-zero vibration amplitude, which are mechanical vibrations forced by the vibration exciter, at a second useful frequency, which is a vibration frequency corresponding to the second frequency, whereby each of the first and second vibration signals respectively includes a second useful signal component, which a sinusoidal signal component having a signal frequency corresponding to the second useful frequency; and
based upon the signal frequency of at least one of the second useful signal components, and/or based upon a signal amplitude of at least one of the second useful signal components, and/or based upon a phase angle of at least one of the second useful signal components, monitor a quality of the measured substance, including to determine whether a fault of the measured substance is present, which is an undesired change of one or more substance parameters of the measured substance.
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