Capacitance Water Level Sensor Debris Resistance
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Solution Overview
Problem
Mechanical water level sensing apparatuses in liquid tanks are prone to mechanical defects, debris accumulation, and increased fabrication costs, with electronic sensors on outer walls being susceptible to moisture and debris-induced malfunctions.
Innovation Solution
A capacitance-based water level sensing apparatus with a smooth, hermetically sealed design using a printed board assembly (PBA) capacitance detecting unit, where the body's thickness varies to differentiate capacitance values for accurate water level detection, minimizing external contamination and cleaning needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical water level sensing apparatus with float is used, then water level detection is achieved, but mechanical defects and debris accumulation occur
Solution Approach 1:
The patent replaces the mechanical float-based sensing system with an electronic capacitance sensing system. The capacitance sensor detects water level changes through electrical field variations rather than mechanical float movement, eliminating the float structure that accumulates debris. This substitution resolves the contradiction by maintaining detection reliability while removing the mechanical components that are prone to debris accumulation and mechanical defects.
Solution Approach 2:
The patent extracts and removes the float and magnet components from the water level sensing system, keeping only the essential capacitance sensing function. By taking out the mechanical float structure that is susceptible to debris accumulation, the system achieves reliable detection without the harmful effects of debris encrustation on moving parts.
2Reliability
If a mechanical water level sensing apparatus is used, then water level detection is achieved, but the structure becomes complicated and costly
Solution Approach 1:
The patent replaces the complex mechanical float assembly with a simple capacitance sensor mounted on the tank wall. This substitution dramatically reduces structural complexity while maintaining or improving detection reliability, as the electronic sensor has no moving parts and requires no mechanical support structures within the water tank.
Solution Approach 2:
The patent extracts the float, magnet, and associated mechanical support structures from the system, retaining only the essential capacitance sensing element. This extraction simplifies the overall device structure and reduces fabrication costs by eliminating complex mechanical components and their assembly requirements.
3Ease of manufacture
If a capacitance sensor is installed on the outer wall surface of the liquid tank, then water level detection is achieved, but malfunctions occur due to moisture and debris
Solution Approach 1:
The patent employs a protective coating or sealing layer (analogous to flexible shell principle) on the capacitance sensor and its mounting structure. This protective barrier prevents moisture and debris from directly contacting the sensor elements, thereby maintaining sensor reliability while allowing the sensor to remain installed on the outer wall surface for ease of manufacture and installation.
4Reliability
If structures are installed within the liquid tank, then water level sensing is achieved, but the structures become covered with dirt and require frequent cleaning
Solution Approach 1:
The patent replaces the mechanical float structure that extends into the water tank with an electronic capacitance sensor mounted on the outer tank wall. This substitution eliminates the internal mechanical structure that would accumulate dirt, thereby maintaining sensing accuracy while eliminating the need for frequent cleaning of internal components.
Solution Approach 2:
The patent extracts the sensing structure from the interior of the water tank and relocates it to the outer wall surface. By taking out the float and magnet from the tank interior, the system maintains sensing accuracy through the capacitance effect while eliminating the problem of dirt accumulation on internal structures.
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
The solution prevents debris accumulation, reduces cleaning frequency, and minimizes malfunctions due to external influences, while lowering fabrication costs and eliminating mechanical components that can cause defects.
Implementation Method 1
the capacitance sensor or the like that senses the level of liquid by detecting a change in capacitance
Implementation Method 2
senses the level of liquid by detecting a change in capacitance
Data Source
Figure 1~2
Figure 3
AI summary
There is provided a water level sensing apparatus including: a body disposed to be exposed within a liquid tank and having an accommodating space therein; and a capacitance detecting unit accommodated in the accommodating space of the body, wherein the capacitance detecting unit compares an upper side capacitance value and a lower side capacitance value and turns on or off an output signal. Because a changeable reference that the capacitance values of a reference surface and a detected surface of the body are simultaneously changed is used, even if the body comes in contact with moisture or debris, the reference surface and the detected surface are equally affected by the moisture or debris, thus reducing the occurrence of malfunction.