Electrode-Based Liquid-Level Sensor for Float-Free Appliances
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Solution Overview
Problem
Existing liquid level sensors in household appliances, such as washing machines, face issues with reliability due to mechanical float systems that can become blocked or inert, leading to delayed activation and inaccuracy in detecting liquid levels, especially under turbulent conditions.
Innovation Solution
A purely electrical sensor system using electrodes with varying resistance based on liquid conductivity, eliminating mechanical parts and utilizing a floating electrode to ensure precise and reliable detection without mechanical movements or inaccuracies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical float system is used for liquid level detection, then the construction is simple and cost is low, but the reliability is limited due to blockage risk and mechanical inertia
Solution Approach 1:
The patent replaces the mechanical float system with an electrical sensing system using electrodes that detect liquid level through electrical conductivity changes. This substitution eliminates moving parts, blockage risks, and mechanical inertia while maintaining detection functionality, directly resolving the contradiction between reliability and complexity.
Solution Approach 2:
The patent introduces an intermediary electrical field between electrodes to detect liquid level. Instead of direct mechanical contact, the liquid itself acts as the intermediary medium that completes the electrical circuit when reaching certain levels, enabling reliable detection without mechanical components.
2Measurement precision
If a mechanical float system is used, then installation is simple, but detection precision is limited due to float variability and turbulence sensitivity
Solution Approach 1:
The electrical electrode system replaces the mechanical float, eliminating sensitivity to turbulence and float variability. The electrodes provide stable, precise measurements based on electrical conductivity thresholds that are not affected by liquid motion or turbulence.
Solution Approach 2:
The patent changes the detection parameter from mechanical position to electrical conductivity. By measuring electrical resistance or conductivity changes as liquid rises between electrodes, the system achieves higher precision without being influenced by mechanical variations or turbulent conditions.
3Loss of time
If a float-based sensor is used, then the overall cost is low, but response time is delayed due to mechanical inertia
Solution Approach 1:
The electrical sensing system responds instantaneously to liquid level changes through electrical conductivity changes, eliminating the mechanical inertia that causes delayed response in float systems. This immediate response prevents flooding while maintaining system reliability.
4Area of stationary object
If electrodes are positioned close together for compact design, then footprint is reduced, but detection accuracy may be affected by liquid turbulence
Solution Approach 1:
The patent uses electrical conductivity as the detection parameter, which is inherently insensitive to liquid turbulence. Even with compact electrode spacing, the electrical field detection method maintains accuracy because it measures conductivity thresholds rather than mechanical displacement, eliminating turbulence-related errors.
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 electrical sensor system provides continuous, accurate, and reliable liquid level detection, reducing the risk of blockages and inertia, and offering high precision and modularity with low costs and small dimensions, suitable for various household appliances with minimal modifications.
Implementation Method 1
an electrical resistance is established between the first electrode (107) and the second electrode (106), said electrical resistance being of a predetermined value and proportionate to said predetermined difference in potential (V) in a situation in which the level of said liquid in said container is such as not to define any conductive path between said first electrode (107) and said second electrode (106), said electrical resistance being variable as soon as the level of said liquid in the container is such as to establish at least one conductive path between said first electrode (107) and said second electrode (106)
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
A detection sensor (100) for detecting the level of a liquid in a storage container or tank, where said sensor comprises a first detection device (101) comprising a support element (102) adapted to be positioned, at least partially, in the inner space defined by said container and intended for storing or collecting said liquid; where said first device (101) comprises a first electrode (107) and a second electrode (106) supported by said support element (102) in a fixed mutual position; where between said first electrode (107) and second electrode (106), an electrical resistance is established when said first electrode and second electrode are at least partially immersed in (or wetted by) said liquid.