External Vibration Sensor for Liquid Level Detection in Septic Tanks
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Solution Overview
Problem
Existing methods for measuring liquid levels in septic tanks, especially in pleasure boats, are unreliable due to non-homogeneous contents and limited space, and existing external measurement technologies are complex and difficult to implement effectively.
Innovation Solution
A device comprising a first actuator and vibration sensor on the container wall that applies an oscillating force and measures the resulting vibrations to determine the liquid level, using a control unit to compare system responses with known responses to accurately assess liquid presence and level, even in non-homogeneous contents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a float is arranged inside the septic tank to measure liquid level, then the liquid level can be measured, but the measurement becomes unreliable due to non-homogeneous contents and limited space
Solution Approach 1:
The measurement system is extracted from the interior of the septic tank and placed on the exterior wall. The actuator and vibration sensor are mounted on the container wall, allowing measurement without introducing parts into the tank interior, thus avoiding interference from non-homogeneous contents and limited space
Solution Approach 2:
The container wall serves as an intermediary medium between the external measurement devices and the liquid contents. The actuator applies vibration through the wall, and the sensor detects vibrations transmitted through the wall, allowing indirect measurement of liquid level without direct contact with the non-homogeneous contents
2Reliability
If external measurement equipment is installed on the container wall, then parts do not need to be introduced into the tank, but the measurement system becomes relatively complicated
Solution Approach 1:
The actuator and vibration sensor are combined into a single measurement unit mounted on the container wall. This integrated approach reduces the number of separate components and simplifies installation while maintaining measurement reliability through external measurement
Solution Approach 2:
The system uses mechanical vibration as the measurement principle, which is a well-established and relatively simple physical phenomenon. The actuator generates vibrations and the sensor detects them, providing a straightforward measurement mechanism that avoids complex electronic or optical systems
3Measurement precision
If vibration measurement is used to detect liquid level, then reliable measurement is achieved, but the system requires comparison with earlier measured responses to determine liquid level
Solution Approach 1:
The system performs preliminary measurements when the liquid level is known (e.g., when the tank is empty or full) and stores these reference responses. During normal operation, current measurements are compared against these pre-established references to determine liquid level, simplifying real-time decision-making
Solution Approach 2:
The system uses feedback by continuously comparing current vibration measurements with reference measurements from known states. This feedback mechanism allows the system to adapt to variations in the container and environmental conditions while maintaining accurate liquid level determination
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
Provides reliable liquid level measurements without introducing parts into the septic tank, suitable for metal containers like aluminum and stainless steel, and is robust against non-homogeneous contents, preventing leaks and ensuring timely emptying.
Implementation Method 1
The transmitter excites a vibration pulse in the tank wall, which vibration pulse is detected by the receiver
Implementation Method 2
The transmitter excites a vibration pulse in the tank wall, which vibration pulse is detected by the receiver. By measuring the change in the phase velocity of the vibration wave
Data Source
Figure 1~2
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Figure 5~6
AI summary
A measurement device (3) and a method for determination regarding the liquid level in a container (1) with a wall (2) is described. A force is applied in a point on the wall on the outside of the container (1) and the resulting impulse response is measured and calculated. From the impulse response a determination is made regarding the liquid level in the container.