Adjustable Reference Element for Oscillatory Process Variable Measurement
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Solution Overview
Problem
Existing devices for monitoring process variables like fill level, density, and viscosity in containers face challenges due to interference signals from charging and discharging currents in piezo elements, which are not fully compensated by reference capacitors due to differing temperature and aging behaviors.
Innovation Solution
A device with an electromechanical converter unit and a reference element of adjustable size, where the second component is structurally identical to the first, allowing for optimal time constant adjustment to minimize interference signals and enhance measurement accuracy, using digital potentiometers to set the time constant and determine temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reference capacitor is used to compensate charging and discharging currents, then interference signals are reduced, but temperature and aging behavior differences cause incomplete compensation
Solution Approach 1:
The patent changes the parameters of the reference element by making its capacitance electrically adjustable. This allows the reference element's time constant to be adapted to match the converter element's time constant under different operating conditions, particularly temperature variations. The electrically adjustable capacitance enables dynamic parameter matching between the reference element and converter element, ensuring complete compensation of charging and discharging currents across the entire operating range.
Solution Approach 2:
The patent introduces dynamics into the reference element by making its capacitance可调 (adjustable). Instead of a fixed capacitor with static parameters, the reference element can dynamically change its capacitance value to match the converter element's varying time constant. This dynamic adaptation ensures that the reference element continuously tracks the converter element's behavior under changing temperature and aging conditions, achieving reliable and complete compensation.
2Device complexity
If a fixed reference capacitor is used, then the device structure is simple, but it cannot adapt to temperature-dependent time constant changes
Solution Approach 1:
The patent transforms the static reference capacitor into a dynamic element with electrically adjustable capacitance. This allows the reference element to adapt its parameters to match the converter element under varying temperature conditions. The adjustable capacitance enables the system to maintain accurate compensation across the entire operating temperature range without significantly increasing structural complexity.
Solution Approach 2:
The patent changes the reference element's capacitance parameter from fixed to variable. By making the capacitance electrically adjustable, the reference element can modify its time constant to match the converter element's temperature-dependent time constant. This parameter change enables the system to adapt to temperature variations while maintaining a relatively simple overall structure.
3Measurement precision
If the reference element and converter element have different time constants, then charging and discharging behavior differs, but full compensation of interference signals becomes impossible
Solution Approach 1:
The patent enables parameter matching between the reference element and converter element by making the reference element's capacitance electrically adjustable. This allows the time constants of both elements to be matched under different operating conditions, particularly temperature variations. The adjustable capacitance provides the flexibility needed to achieve complete time constant matching, ensuring full compensation of charging and discharging currents.
Solution Approach 2:
The patent introduces dynamics into the reference element, allowing its capacitance and consequently its time constant to be adjusted to match the converter element's time constant. This dynamic matching capability ensures that the reference element's charging and discharging behavior always mirrors that of the converter element, enabling complete compensation of interference signals across the entire operating range.
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 solution significantly increases measuring accuracy by effectively eliminating interference signals and accounting for temperature-dependent changes, ensuring precise determination of process variables across varying conditions.
Implementation Method 1
an electromechanical converter unit (4) with at least one piezoelectric converter element (41), which excites the oscillatable unit (3) to mechanical oscillations by means of an excitation signal
Implementation Method 2
receives vibrations from the oscillatable unit (3) and converts them into an electrical reception signal
Implementation Method 3
inductive converter element, which excites the oscillatable unit (3) to mechanical oscillations
Data Source
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AI summary
Device for determining and/or monitoring at least one process variable of a medium (21) in a container (22), comprising a mechanically oscillatable unit (3), an electromechanical converter unit (4) which has at least one piezoelectric or inductive converter element (41), causes the oscillatable unit (3) to oscillate mechanically under the effect of an excitation signal (AS), and receives oscillations from the oscillatable unit (3) and converts said oscillations into an electrical receive signal (ES), a reference element (5) having a first component (42) operated using an electrically adjustable variable, wherein said reference element (5) is connected in parallel to the electromechanical converter unit (4), is impinged upon by the same excitation signal (AS), and generates a reference signal (RS) that is not influenced by the oscillations of the oscillatable unit (3), and an electronic unit that extracts a useful signal (NS) from the receive signal (ES) and the reference signal (RS) and uses said useful signal (NS) to determine and/or monitor the process variable. According to the invention, the electromechanical converter unit (4) has a second component (42) operated using an electrically adjustable variable.