Water Level Measurement Device Sloshing Filter
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Solution Overview
Problem
Conventional liquid level measuring apparatuses face difficulties in accurately determining the liquid level when the surface is sloshing, especially in moving vehicles where multi-directional acceleration causes irregular fluctuations, leading to inaccurate measurements.
Innovation Solution
A liquid level measuring technique that applies a filter with a time constant greater than one second to the water level signal from a water level indicator, retaining the minimum value of the filter output as the final water level to minimize the influence of sloshing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional water level indicator is used to measure liquid level, then the measurement is accurate when the liquid surface is stable, but the measurement becomes inaccurate when the liquid surface is sloshing due to multi-directional acceleration
Solution Approach 1:
The patent applies a filter with a time constant greater than one second to the water level signal, changing the temporal parameter of the measurement system. This filtering operation transforms the raw water level signal into a filtered signal that represents the minimum value over time, effectively separating the actual water level trend from the sloshing fluctuations. The parameter change in time constant allows the system to maintain measurement accuracy during sloshing conditions.
2Measurement precision
If the liquid surface is sloshing due to vibrations or multi-directional acceleration, then the liquid level fluctuates up and down irregularly, but the actual liquid level gradually drops as liquid is consumed
Solution Approach 1:
The patent extracts the minimum value component from the filtered water level signal, separating it from the sloshing-induced fluctuations. By retaining only the minimum value of the filtered signal over time, the system extracts the true water level trend while eliminating the harmful sloshing components. This extraction process allows accurate detection of the actual water level despite surface irregularities.
Solution Approach 2:
The filter with time constant greater than one second acts as an intermediary between the raw water level indicator signal and the final measured value. This intermediary filtering operation smooths out the sloshing fluctuations while preserving the underlying water level trend, enabling accurate measurement despite the harmful effects of liquid sloshing.
3Speed
If no filtering is applied to the water level signal, then the measurement responds quickly to changes, but the measurement includes significant noise from surface fluctuations
Solution Approach 1:
By selecting a filter time constant greater than one second, the patent optimizes the balance between response speed and measurement precision. This parameter setting allows the system to respond to actual water level changes while filtering out high-frequency sloshing noise, achieving both adequate response speed and improved signal-to-noise ratio.
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 improves measurement accuracy by stabilizing the water level reading, as the actual liquid level tends to align with the minimum filter value, reducing the impact of surface fluctuations and ensuring accurate liquid level detection even during sloshing.
Implementation Method 1
a technique for indirectly measuring the water level based on a change in an interelectrode capacitance of a pair of electrodes arranged with a predetermined gap therebetween
Data Source
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AI summary
A water level measuring apparatus and a water level measuring method, in which a water level L0 of a liquid is read from a water level indicator secured to a liquid tank, and a filter value FLT is calculated by applying a filter with a time constant greater than one second to the water level L0. Furthermore when the filter value FLT is less than a minimum value Min, the minimum value Min is sequentially updated with the filter value FLT. Then the minimum value Min is output as the final water level L. Accordingly, even if the surface sloshes and the water level L0 fluctuates up and down, by adopting the minimum value that utilizes the characteristic of the surface fluctuations, as the final water level L, there is little influence of the liquid sloshing, and the water level measurement accuracy can be improved.