Liquid Level Sensor Using Dynamic Pressure Fluctuations
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Solution Overview
Problem
Existing liquid level detection methods, such as pneumatically acting sensor devices, are sluggish and lack precision in recording specific liquid levels, and often require pressure relief valves to protect switches from overpressure, which can be cumbersome.
Innovation Solution
The sensor device employs dynamic pressure fluctuations in the supply line to differentiate between the presence and absence of liquid at the outlet by analyzing the flow behavior of the feed substance, using pressure fluctuations over time to provide precise measurements without the need for pressure relief valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If static hydrostatic pressure is used for liquid level detection, then the measurement is simple to implement, but the precision for detecting specific liquid levels is insufficient and the response is sluggish
Solution Approach 1:
The patent transitions from static pressure measurement to dynamic pressure fluctuation analysis. By evaluating the temporal characteristics of pressure fluctuations rather than a single static pressure value, the system achieves more precise liquid level detection. The dynamic approach allows differentiation between various liquid levels based on the characteristic patterns of pressure variations over time.
Solution Approach 2:
The patent utilizes periodic pressure fluctuations caused by liquid interaction with the supply line outlet. The periodic nature of these fluctuations provides characteristic signals that can be analyzed to determine precise liquid levels. The regular pattern of pressure changes enables more accurate measurement compared to static pressure alone.
2Reliability
If compressed air is supplied through a supply line outlet into the liquid, then liquid level can be detected, but pressure build-up occurs when the outlet is clogged requiring pressure relief valves
Solution Approach 1:
The patent replaces the mechanical pressure relief valve with an electronic/software-based solution. Instead of using a physical valve to relieve excess pressure, the system monitors pressure fluctuations and uses evaluation means to detect clogging conditions. When clogging is detected, the system can alert operators or automatically adjust operations, eliminating the need for additional mechanical safety components.
3Extent of automation
If a membrane switch is installed in the supply line to detect specific pressure levels, then automatic level switching is achieved, but pressure relief valves are required to protect the switch from overpressure
Solution Approach 1:
The patent replaces mechanical switches with electronic sensing and evaluation systems. The pressure fluctuations are detected by sensors and processed by evaluation means that can automatically determine liquid levels and trigger switching actions. This electronic approach provides automatic level switching without requiring mechanical switches that would need pressure relief protection.
Solution Approach 2:
The patent introduces evaluation means as an intermediary between the pressure detection and the switching action. This intermediary layer analyzes the pressure fluctuation patterns and makes intelligent decisions about when switching should occur, providing more reliable and flexible automation compared to direct mechanical switch actuation.
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 allows for precise detection of liquid levels, reducing the need for pressure relief valves and enhancing measurement accuracy by utilizing dynamic pressure changes, which are easier to implement and more reliable than static pressure evaluations.
Implementation Method 1
the higher this extends over the outlet, the higher the hydrostatic pressure at the outlet and thus the counter-pressure acting on the air in the supply line
Implementation Method 2
By detecting the pressure fluctuations, conclusions can be drawn about the corresponding characteristic, and the state in which the liquid is not present at the outlet can thus be distinguished from the state in which the liquid is present at the outlet
Data Source
Figure 1~3
Figure 4~6
AI summary
The sensor device serves to detect the absence or presence of a liquid (1) at the outlet (10a) of a supply line (10) through which a feed substance can be supplied. Upon exiting the outlet, the feed substance exhibits a pressure (p) in the supply line. In the absence of the liquid, this pressure has a first characteristic over time, and in the presence of the liquid, it has a second characteristic over time. The sensor device comprises sensing means (20-23) for detecting the pressure fluctuations in the supply line (10) and evaluation means (30) configured to assign the detected pressure fluctuations to the first or second characteristic and to generate a corresponding signal indicating whether the liquid (1) is absent or present at the supply line outlet (10a).