Oscillatory Density Sensor Phase Control Viscosity Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing devices that measure density using oscillatory forks face challenges in distinguishing density from viscosity due to their dual dependence on these medium properties, making accurate density monitoring difficult.
Innovation Solution
The electronics unit generates an exciter signal that creates a phase difference with the received signal, which is predetermined based on the ratio of the impedance of the exciting/receiving unit to the input impedance of the electronics unit, effectively eliminating the effects of viscosity changes on mechanical oscillations, allowing for reproducible density measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If oscillatory forks are used to measure medium properties, then both density and viscosity information are obtained, but the dual dependence on density and viscosity makes density measurement difficult
Solution Approach 1:
The patent applies parameter changes by adjusting the phase difference between exciter and received signals to a specific value (70° for liquid media) that eliminates viscosity effects on frequency measurements. This phase parameter adjustment transforms the measurement system to be insensitive to viscosity changes, allowing accurate density measurement without complex separation algorithms
Solution Approach 2:
The invention extracts only the density information from the oscillation measurements by eliminating viscosity effects through phase difference control. By setting the phase difference to a predetermined value, the system separates density measurement from viscosity influence, obtaining pure density data without needing to process both parameters simultaneously
2Measurement precision
If phase difference is adjusted to eliminate viscosity effects, then density measurement accuracy is improved, but additional control complexity is introduced
Solution Approach 1:
The electronics unit automatically maintains the desired phase difference between exciter and received signals through self-regulating control. The system monitors the actual phase difference and adjusts it to match the predetermined value, eliminating the need for manual calibration or complex external control mechanisms
Solution Approach 2:
The patent implements feedback control where the electronics unit continuously monitors the phase difference between exciter and received signals and adjusts the phase to maintain the predetermined value. This closed-loop feedback ensures consistent elimination of viscosity effects while simplifying operation through automatic adjustment
3Reliability
If impedance ratio is considered in phase difference determination, then measurement reliability is improved, but calculation complexity increases
Solution Approach 1:
The patent performs preliminary determination of the desired phase difference based on the impedance ratio of the exciting/receiving unit to the electronics unit input impedance. By calculating and storing the appropriate phase difference value in advance for given impedance conditions, the system ensures measurement reliability without requiring complex real-time calculations during operation
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 approach enables precise measurement of density by maintaining a phase difference that negates viscosity effects, resulting in accurate and reliable density monitoring, even when viscosity changes occur.
Implementation Method 1
The exciting/receiving unit is, in an embodiment, a piezoelectric element, which converts the exciter signal (SE), which is an electrical, alternating voltage, into mechanical oscillations.
Implementation Method 2
at least one mechanically oscillatory unit; at least one exciting/receiving unit, which excites the mechanically oscillatory unit, such that it executes mechanical oscillations
Data Source
AI summary
An apparatus for ascertaining and/or monitoring a process variable, especially density of a medium. The apparatus includes: an exciting/receiving unit, which excites a mechanically oscillatable unit to execute mechanical oscillations and which receives the mechanical oscillations; an electronics unit, which applies to the exciting/receiving unit an electrical, exciter signal, and which obtains from the exciting/receiving unit an electrical, received signal. The electronics unit produces the exciter signal in such a manner, that, between the received signal and the exciter signal, a phase difference equal to a desired value of phase difference results, at which effects of changes of viscosity on mechanical oscillations of the mechanically oscillatable unit are negligible, and that the desired value of phase difference is predetermined as a function of the ratio of impedance of the exciting/receiving unit to the input impedance of the electronics unit.