Coriolis Flowmeter Tube Mounting for Vibration Immunity

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Solution Overview

Problem

Measuring transducers with a single measuring tube are highly sensitive to external influences such as clamping and vibration forces, leading to increased measuring errors due to poor mechanical common-mode suppression and immunity to interference.

Innovation Solution

The measuring transducer design eliminates free tube segments between measuring tubes, mechanically connecting the measuring tube and inner carrier element directly to the outer carrier element, ensuring both react uniformly to external disturbances, thereby preventing oscillating movements relative to the useful frequency and reducing interference components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If measuring transducer uses free tube segments between measuring tubes to allow vibration, then the measuring tube can oscillate to generate Coriolis forces, but the transducer becomes highly sensitive to external influences such as clamping and vibration forces

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidsensitivity to external influences
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent removes the free tube segments between the measuring tubes and the support elements, extracting the source of mechanical instability. By eliminating these free segments, the measuring tubes are directly supported at their ends, preventing unwanted oscillations and improving immunity to external disturbances while maintaining the ability to vibrate in the useful mode for measurement.

Inventive Principle:
Principle #2Taking out (Extraction)

2Adaptability or versatility

If measuring transducer includes inner carrier element oscillating relative to outer carrier element, then the transducer can be balanced over large density ranges, but mechanical common-mode suppression deteriorates

Engineering Contradiction:
Improvebalancing capability over density rangesVSAvoidmechanical common-mode suppression
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent merges the inner carrier element with the outer carrier element by eliminating relative oscillation between them. The measuring tubes are directly supported by the outer carrier element without intermediate free segments, creating a unified mechanical structure that suppresses common-mode vibrations and improves measurement precision while maintaining adaptability through the Coriolis measurement principle.

Inventive Principle:
Principle #5Merging (Combining)

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

This design significantly improves mechanical common-mode rejection, reducing measuring errors and enhancing immunity to external disturbances, maintaining measurement accuracy despite varying medium densities.

Implementation Method 1

These oscillations are excited at a momentary resonant frequency of the same mode, for example, with a practically constant amplitude.

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 2

the useful vibrations generate Coriolis forces as a result of the medium flowing through the measuring tube oscillating in the useful mode. These forces, in turn, cause further Coriolis vibrations—namely, additional vibrations of the measuring tube in the so-called Coriolis mode

Methodology Applied
Scientific EffectCoriolis force: Coriolis Force

Data Source

PatentEP2938973B1Vibration-type measuring transducer and measuring system formed therefrom
Publication Date: 2023.05.03 ENDRESS HAUSER FLOWTEC AG
  • EP2938973B1 patent drawingFigure 1
  • EP2938973B1 patent drawingFigure 2
  • EP2938973B1 patent drawingFigure 3

AI summary

The measuring transducer comprises: a measuring tube (M) having a tube end (M+) on the inlet side and a tube end (M#) on the outlet side, said measuring tube having a tube wall with a defined wall thickness and a lumen extending between the first and the second tube ends and being surrounded by said tube wall; a supporting element (TE) which is mechanically connected by one supporting end (TE+) to the tube end (M+) and by one supporting end (TE#) to the tube end (M#); and a supporting element (TS) positioned at a lateral distance from the measuring tube and mechanically connected by one supporting end (TS+) to the supporting end (TE+) and by one supporting end (TS#) to the supporting end (TE#). The measuring tube of the measuring transducer is designed to conduct a flowing medium in the lumen and at the same time to be capable of oscillation around a static resting position in order to generate Coriolis forces. In addition, the measuring transducer comprises an oscillator (E) and at least one oscillation sensor (S1; S2). The measuring transducer has a natural innate working mode with a resonant frequency, in which mode the measuring tube (M) can carry out working oscillations around a static resting position at a working frequency corresponding to the resonant frequency of the working mode, said oscillations being suitable for generating Coriolis forces. The oscillator (E) is further designed to induce said working oscillations of the measuring tube and the oscillation sensor, one sensor component (SV) of which being attached to the exterior of the measuring tube (M) and one sensor component (SV) being attached to the supporting element (TS), is designed to detect movements of the measuring tube (M) relative to the supporting element (TS) and to convert said movements into an oscillation signal representing the oscillations of the measuring tube.