Liquid Level Probe Baseline Sensing for Filtered Water Detection
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Solution Overview
Problem
Existing liquid level sensing systems in beverage forming systems face challenges in detecting water levels with highly filtered water and suffer from inaccuracies due to scale or deposit buildup, leading to unpredictable resistance changes in the probe circuit.
Innovation Solution
A method that measures a baseline characteristic of the probe circuit when the probe is out of contact with liquid and updates it during the fill operation, allowing for accurate detection of liquid levels by comparing subsequent measurements to this baseline, effectively accounting for changes caused by scale or deposits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive probe is used to detect water level by determining circuit resistance, then liquid level detection is enabled, but the system fails to reliably detect water levels with highly filtered water due to high resistance
Solution Approach 1:
The system performs preliminary characterization of the probe circuit by measuring resistance at multiple known water levels and storing these baseline values. This preliminary action enables the system to account for circuit variations due to scale buildup or filtered water conditions, allowing reliable detection even when absolute resistance values are high or variable.
Solution Approach 2:
The system changes the measurement approach from using absolute resistance thresholds to using relative resistance changes compared to baseline values. By characterizing the circuit at different water levels and comparing subsequent measurements against these baselines, the system adapts to changing conditions such as scale accumulation or water conductivity variations.
2Duration of action of stationary object
If scale or deposits build up on the probe and tank walls, then the probe circuit resistance changes over time, but this causes unpredictable variations in detection accuracy
Solution Approach 1:
The system performs preliminary characterization of the probe circuit by measuring resistance at multiple known water levels and storing these baseline values. This preliminary action enables the system to account for circuit variations due to scale buildup or filtered water conditions, allowing reliable detection even when absolute resistance values are high or variable.
Solution Approach 2:
The system continuously monitors probe circuit resistance and compares it against stored baseline values from preliminary characterization. This feedback mechanism allows the system to detect water level changes relative to the established baselines, compensating for gradual resistance changes caused by scale accumulation over the system's operational lifespan.
3Ease of operation
If an absolute resistance threshold is used for detection, then the system is simple to operate, but it cannot adapt to changing circuit conditions over time
Solution Approach 1:
The system performs preliminary characterization of the probe circuit by measuring resistance at multiple known water levels and storing these baseline values. This preliminary action enables the system to account for circuit variations due to scale buildup or filtered water conditions, allowing reliable detection even when absolute resistance values are high or variable.
Solution Approach 2:
The system changes the measurement approach from using absolute resistance thresholds to using relative resistance changes compared to baseline values. By characterizing the circuit at different water levels and comparing subsequent measurements against these baselines, the system adapts to changing conditions such as scale accumulation or water conductivity variations.
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 reliable detection of liquid levels even with highly filtered water and in the presence of scale or deposits, improving the accuracy and consistency of liquid level sensing over the system's lifespan.
Implementation Method 1
a conductive probe may be used to detect the presence of the water in the tank by determining whether the resistance of a circuit including the probe drops below an absolute threshold
Data Source
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AI summary
A liquid level sensing arrangement using a probe uses a baseline probe circuit characteristic, e.g., a circuit resistance or voltage, that is measured when the probe is out of contact with the liquid in the tank. The baseline characteristic may be used to determine a liquid level in the tank, e.g., a determination whether the liquid level is below or at/above the probe. In one embodiment, the baseline characteristic may be compared to a circuit characteristic that is measured as the tank is being filled. A difference between the baseline characteristic and the other circuit characteristic may be used to determine whether or not the probe is in contact with the liquid.