Fluid Level Sensor Resonant Frequency Detection via Segmented Excitation

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Solution Overview

Problem

Existing point level sensors, particularly vibration and impedance sensors, face challenges in quickly and reliably determining the resonant frequency, especially in high-viscosity media, leading to incorrect state differentiation between 'blocked' and 'covered' conditions, and inefficient energy coupling due to limited frequency excitation methods.

Innovation Solution

A method that subdivides the frequency range into sub-ranges for sequential excitation and frequency response detection, allowing for reliable resonance frequency detection even in high-viscosity media, and dynamically adjusts sub-ranges when the resonant frequency shifts, ensuring sufficient energy coupling and quick determination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a continuous frequency sweep over the entire frequency range is performed to excite the vibration point level sensor, then the resonant frequency can be reliably determined, but the measurement time increases and energy consumption increases

Engineering Contradiction:
Improvereliability of resonant frequency determinationVSAvoidmeasurement time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The frequency range is divided into multiple sub-ranges (first sub-range, second sub-range, etc.), each covering a specific portion of the total frequency spectrum. The sensor is excited sequentially in each sub-range rather than performing a continuous sweep across the entire range, which reduces measurement time while maintaining reliable resonant frequency detection through systematic coverage of all frequency portions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The method performs preliminary excitation in the first sub-range to obtain an initial frequency response before proceeding to the second sub-range. This staged approach allows the system to gather information incrementally and determine the resonant frequency more efficiently by eliminating frequency portions that do not contain the resonance peak, rather than sweeping through all frequencies uniformly.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If a continuous frequency sweep over the entire frequency range is performed, then the resonant frequency can be reliably determined, but energy consumption increases

Engineering Contradiction:
Improvereliability of resonant frequency determinationVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The frequency range is segmented into multiple sub-ranges with sequential excitation. By limiting each excitation pulse to a specific sub-range rather than continuously sweeping the entire frequency range, the total energy required to excite the sensor is significantly reduced while still ensuring the resonant frequency is captured through systematic coverage of all sub-ranges.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The excitation is applied periodically in discrete pulses to each sub-range rather than continuously across the entire frequency spectrum. This periodic, pulsed excitation approach reduces average power consumption compared to continuous sweeping, while the sequential progression through sub-ranges ensures complete frequency coverage for reliable resonant frequency determination.

Inventive Principle:
Principle #19Periodic action

3Use of energy by moving object

If the vibration point level sensor is excited with a fixed frequency, then energy consumption is reduced, but the resonant frequency may not be sufficiently excited if it shifts

Engineering Contradiction:
Improveenergy consumptionVSAvoidreliability of resonant frequency detection
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The excitation frequency is made dynamic by adapting it to the specific sub-range being measured. Rather than using a single fixed frequency or a continuous sweep, the system dynamically adjusts the excitation frequency to match each sub-range, optimizing energy efficiency for each measurement phase while maintaining the ability to detect resonant frequency shifts through systematic coverage of multiple frequency regions.

Inventive Principle:
Principle #15Dynamics

4Loss of time

If the frequency range is subdivided into sub-ranges for sequential excitation, then measurement time is reduced, but the device complexity increases

Engineering Contradiction:
Improvemeasurement timeVSAvoidcomplexity of frequency excitation control
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The frequency range is divided into discrete sub-ranges with defined boundaries. This segmentation simplifies the control logic by creating clear, manageable measurement stages rather than requiring complex continuous frequency modulation. Each sub-range can be excited independently with simple pulse generation, reducing the overall control complexity compared to managing a continuous sweep across the entire frequency spectrum.

Inventive Principle:
Principle #1Segmentation

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

Enables rapid and accurate detection of the resonant frequency in both vibration and impedance sensors, improving signal amplitude and reducing measurement time, especially in high-viscosity conditions, and differentiating between 'blocked' and 'covered' states effectively.

Implementation Method 1

the resonance frequency of an oscillating system is determined... in which the oscillating system is excited in a frequency range between a lower limit frequency and an upper limit frequency and a frequency response is then detected

Methodology Applied
Scientific EffectResonance: Resonance

Data Source

PatentEP3450933B1Method of operating a fluid level threshold sensor
Publication Date: 2022.07.06 VEGA GRIESHABER GMBH & CO
  • EP3450933B1 patent drawingFigure 1a~1b
  • EP3450933B1 patent drawingFigure 2
  • EP3450933B1 patent drawingFigure 3a~3b

AI summary

Method for operating a level sensor, wherein the level sensor is used to determine a resonance frequency (fres) of a vibration system by exciting the vibration system in a frequency range between a lower cutoff frequency (fmin) and an upper cutoff frequency (fmax) and subsequently detecting a frequency response (E), wherein the frequency range is divided into a plurality of sub-ranges (I, II, III, IV,...,n) and, if the resonance frequency (fres) is unknown, the vibration system is sequentially excited in successive sub-ranges (I, II, III, IV,..., n) and the frequency response (EI, EII, EIII, EIV,..., En) is detected after each sub-range (I, II, III, IV,..., N) and, if the resonance frequency (fres) is known, the vibration system is excited only in the sub-range (N) in which the resonance frequency (fres) lies and the frequency response (En) is subsequently detected.