Narrow Band Oscillation for Reliable Level Detection
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Solution Overview
Problem
Existing vibronic point level detection devices are complex and costly due to the need for stable phase behavior and high signal dynamics over a wide frequency range, especially when dealing with non-Newtonian fluids and materials that cause damping.
Innovation Solution
A device with an electronics unit that excites a mechanically oscillatable unit using a narrow frequency band below the resonant frequency, detecting vibrations exceeding a threshold to determine fill levels, and using a second frequency band to detect corrosion by checking for resonant frequency shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resonant circuit electronics with wide frequency range are used to ensure stable oscillation under strong damping, then oscillation reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent changes the frequency parameter from a wide frequency range to a fixed resonant frequency. The electronics are designed to operate at a specific resonant frequency determined during manufacturing, eliminating the need for complex wide-frequency-range circuitry while maintaining reliable oscillation through frequency stabilization means.
Solution Approach 2:
The patent combines the drive and receive functions into a single piezoelectric element that serves both to excite oscillation and to detect it. This multi-functional approach reduces the number of separate components needed in the electronics, simplifying the overall device while maintaining reliable oscillation detection.
2Measurement precision
If precision components for phase and gain determination are used to guarantee correct switching behavior, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent stabilizes the oscillation frequency to a fixed resonant frequency, which eliminates the need for complex phase and gain determination circuits. With a fixed frequency, the switching behavior can be reliably determined using simpler electronics, as the phase relationship is inherently stable at resonance.
Solution Approach 2:
The piezoelectric element itself provides the frequency stabilization through its inherent resonant properties. The system uses the natural resonant frequency of the oscillating unit as the reference, eliminating the need for external precision components to establish and maintain the correct phase and gain relationships.
3Device complexity
If a narrow frequency band around resonant frequency is used for excitation, then device complexity is reduced, but detection capability may be limited
Solution Approach 1:
The patent uses feedback means that compare the received signal with the excitation signal to detect oscillation. This feedback mechanism ensures reliable detection of the resonant frequency oscillation, maintaining detection capability despite the narrow frequency band, as the system actively monitors and responds to the specific resonant frequency.
Solution Approach 2:
The patent exploits the mechanical resonance of the oscillating unit at its natural resonant frequency. By exciting the system at this specific frequency and detecting the resulting mechanical vibrations, the system achieves reliable level detection without requiring a wide frequency band, as the resonant oscillation provides a strong, easily detectable signal.
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 simplifies the device structure, reduces costs, and allows for reliable and quick detection of fill levels and corrosion, while maintaining high reliability and accuracy.
Implementation Method 1
the drive/receiver unit (13) has at least one piezoelectric element, wherein the piezoelectric element serves both as a transmitting element for exciting the mechanically oscillating unit (11) to mechanical vibrations and as a receiving element for receiving the mechanical vibrations
Implementation Method 2
The resonance frequency at standard conditions, as used here and in the following, is the resonance frequency of a vibration in air at normal pressure and room temperature
Data Source
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AI summary
A device (1) for monitoring a predetermined filling level of a medium (3) in a container (2), with a unit (11) capable of mechanical oscillation, with a drive/receiving unit (13) for exciting the mechanically oscillating unit (11) to effect mechanical oscillations and for receiving the oscillations of the mechanically oscillating unit (11), and with an electronic unit (14) for generating an electrical excitation signal and for evaluating an electrical reception signal. The invention is characterised in that the electronic unit (14) is designed to excite the mechanically oscillating unit (11) to oscillate mechanically by means of the drive/receiving unit (13) within a fixedly preset narrow frequency band with discrete successive excitation frequencies, wherein the frequency band contains the resonance frequency of the mechanically oscillating unit (11) during oscillation under standard conditions, and in that the electronic unit (14) is designed to detect whether, within the preset frequency band, there is an oscillation of the mechanically oscillating unit (11), the amplitude of which exceeds a predetermined threshold value.