Tiltable Tank Liquid Level Monitoring via Differential Pressure
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Solution Overview
Problem
Existing liquid level monitoring systems for tiltable tanks, such as aircraft oil tanks, face inaccuracies due to changes in tank attitude and fluid density variations, especially during flight, leading to errors in oil level measurements.
Innovation Solution
A liquid level monitoring system using a pair of pressure sensors located on the tank walls, with one sensor above the other, compensates for tilt and density changes by calculating oil level independently of density using the pressure difference between the two sensors, eliminating the need for an internal detection shaft and allowing for easy installation and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pressure sensors are used to measure liquid level in a tiltable tank, then the measurement system is simple and easy to install, but the measurement accuracy deteriorates due to tank tilt and density variations
Solution Approach 1:
The tank wall is segmented into multiple sensing locations with pressure sensors positioned at different heights. By dividing the measurement task across multiple sensor locations, the system can calculate liquid level while compensating for tilt effects and density variations through comparative analysis of pressure readings from each segment.
Solution Approach 2:
The system changes the measurement parameter from direct pressure reading to pressure difference calculation. By computing the difference in pressure readings between sensors at different heights, the system eliminates the influence of ambient pressure and density variations, achieving accurate liquid level measurement despite tank tilt and environmental changes.
2Measurement precision
If temperature compensation is added to density compensation systems, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The invention extracts and eliminates the need for temperature compensation by using pressure difference measurement. Instead of adding temperature sensors and compensation algorithms, the system takes out the problematic density dependence entirely by measuring pressure differential, which is independent of fluid density and temperature variations.
3Reliability
If an internal detection shaft with multiple sensors is used in a tiltable tank, then liquid level can be monitored during tilt, but the device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
Instead of placing sensors inside the tank on a detection shaft, the invention inverts the approach by placing pressure sensors on the external tank wall. This external mounting approach achieves the same liquid level monitoring function during tilt while dramatically reducing structural complexity and eliminating the need for internal detection shafts.
Solution Approach 2:
The invention replaces the mechanical detection shaft system with a pressure-based sensing system. By using pressure sensors mounted on the tank wall that sense hydrostatic pressure, the system eliminates complex mechanical structures while achieving reliable liquid level monitoring during tank tilt through pressure differential measurement.
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 provides accurate and reliable oil level measurements in tilting tanks by compensating for attitude and density changes, ensuring precise oil level monitoring in aircraft engines despite irregular tank shapes and varying conditions.
Implementation Method 1
the pressure at a point in a liquid is a function of the height of the liquid above that point, the density of the liquid and the pressure of the gas above the liquid
Implementation Method 2
The liquid level is determined from the pressure reading from the first pressure sensor, the pressure reading from the second pressure sensor and the separation distance between the first pressure sensor and the second pressure sensor
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A liquid level monitoring system for monitoring the level of liquid (2) in a tiltable tank (1), which may tilt or rotate in a tilt or rotation plane about a tilt axis (10). The system comprises a pair of pressure sensors comprising a first pressure sensor (9) for sensing the pressure of the liquid in the tank at a first position (7) located towards the bottom of a tank and a second pressure sensor (5) for sensing the pressure of the liquid in the tank at a second position (8) located a known pre-defined distance above the first sensing wherein the two sensing positions (7,8) are located on a sensing line (22) substantially orthogonal to and passing through a liquid surface dividing line (15), said liquid surface dividing line being the line along and extending past the surface of liquid in the tank whose position relative to the tank walls (20) remains the same as the tank tilts about the tilt axis (10).