Coriolis Flowmeter Drive Electronics Switching Oscillation Modes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional Coriolis mass flowmeters experience phase errors due to asymmetric damping of excited oscillations, leading to inaccurate mass flow rate measurements, especially in applications with changing media density and viscosity or inhomogeneous media.
Innovation Solution
A Coriolis mass flowmeter design that includes a measuring transducer with an exciter mechanism and sensor arrangement, where the drive electronics switches between active excitation and free, damped oscillation modes to eliminate disturbance components from the oscillation signals, allowing for accurate phase difference measurement of mass flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If active excitation is applied to the measuring tube, then oscillation amplitude is maintained for continuous measurement, but disturbance components are introduced causing phase errors
Solution Approach 1:
The patent applies periodic action by switching between two operating modes: active excitation mode for oscillation maintenance and free oscillation mode for accurate measurement. The system periodically transitions between these modes, using active excitation only when oscillation amplitude decay would prevent measurement, and free oscillation when accurate phase measurement is required.
Solution Approach 2:
The patent uses preliminary action by maintaining oscillations through active excitation before a measurement cycle begins, ensuring the measuring tube is already oscillating when the measurement sequence starts. This eliminates the need to initiate oscillations during the measurement process, which would introduce disturbance components.
2Productivity
If forced oscillations are used to maintain measuring tube vibration, then continuous measurement is enabled, but asymmetric damping causes phase errors in changing media
Solution Approach 1:
The system periodically alternates between forced oscillation mode (for continuity) and free oscillation mode (for accuracy). During free oscillation periods, the system performs measurements without active excitation, eliminating asymmetric damping effects while maintaining measurement continuity through periodic reacquisition of oscillations.
Solution Approach 2:
The patent extracts the disturbance component (active excitation) from the measurement process. By separating the oscillation maintenance function from the measurement function, the system performs measurements during free oscillation periods when no excitation is applied, thus eliminating the source of phase errors.
3Duration of action of stationary object
If oscillation excitation is continuously applied, then measuring tube vibration is maintained, but disturbance components contaminate the oscillation signals
Solution Approach 1:
The patent implements periodic action by cycling between active excitation phases (for vibration maintenance) and free oscillation phases (for pure signal acquisition). This periodic switching ensures the measuring tube remains oscillating while the measurement is performed during excitation-free intervals when signal purity is maximized.
Solution Approach 2:
The system maintains continuous useful action by ensuring the measuring tube is always oscillating, either through active excitation or free oscillation. The transition between modes is seamless, maintaining vibration continuity while periodically eliminating disturbance components for accurate measurement.
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 prevents phase errors by eliminating disturbance components from the oscillation signals, ensuring precise mass flow rate measurements even in challenging media conditions.
Implementation Method 1
an exciter mechanism (41) adapted to convert electrical power supplied it into mechanical power
Implementation Method 2
Coriolis mass flowmeters... for highly accurate ascertaining of a mass flow rate of a medium... Coriolis forces dependent on the instantaneous mass flow rate are induced in the flowing medium
Implementation Method 3
a sensor arrangement (51, 52) adapted to register mechanical oscillations of the at least one measuring tube and to provide oscillation measuring signals representing oscillatory movements
Data Source
AI summary
The Coriolis mass flowmeter includes a measuring tube, an exciter mechanism, a sensor arrangement, and an electronic transmitter circuit including measuring and control electronics and drive electronics connected to the measuring and control electronics. The drive electronics are adapted, in a first operating mode, to generate an electrical driver signal that supplies electrical power to the exciter mechanism such that the measuring tube executes forced oscillations having an excitation frequency and, in a second operating mode, to cease generating the electrical driver signal. The transmitter circuit is adapted to switch the drive electronics from the first operating mode to the second operating mode such that the measuring tube executes free, damped oscillations in the second operating mode, and the measuring and control electronics are adapted to, based on a phase difference between oscillation measuring signals from the sensor arrangement, to generate measured values representing the mass flow rate.