Liquid Sensing Switch for Bilge Pumps Using RF Capacitive Plates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bilge pump switches are unreliable due to sticking issues in mechanical float-type switches and conductivity problems in electronic switches, particularly in soapy water and oil-water mixtures, leading to improper activation or deactivation of bilge pumps.
Innovation Solution
A liquid sensing switch using RF, analog, and digital circuits with bare uninsulated stainless steel sensor plates driven by a 20 KHz square wave, activated when both plates are covered with bilge water, and deactivated when uncovered, utilizing peak detectors and a NAND gate to control a relay for high current bilge pump operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical float-type switches are used to control bilge pumps, then the switch can detect water levels, but the switch becomes unreliable due to sticking issues
Solution Approach 1:
The patent replaces mechanical float-type switches with an electronic sensing system using RF circuits and sensor plates. This substitution eliminates moving parts that cause sticking, providing reliable operation without mechanical failure modes. The system uses electrical fields and signal processing to detect water levels, completely removing the mechanical operation issues.
Solution Approach 2:
The patent introduces sensor plates as intermediary elements between the water and the control circuitry. These plates detect water presence through capacitive coupling without direct mechanical contact, preventing sticking while maintaining reliable detection. The intermediary sensor plates translate physical water presence into electrical signals for the control system.
2Ease of operation
If electronic switches are used to control bilge pumps, then the switch has no moving parts, but the switch exhibits sticking issues due to conductivity problems in soapy water and oil-water mixtures
Solution Approach 1:
The patent changes the detection parameter from direct electrical conductivity to capacitive coupling. By using sensor plates that detect changes in electrical field characteristics rather than relying on water conductivity, the system becomes immune to the effects of soapy water and oil-water mixtures. This parameter change allows reliable operation across all water types without conductivity-related sticking.
Solution Approach 2:
The patent replaces conductivity-based electronic switching with RF-based capacitive sensing. This substitution uses electromagnetic fields and signal frequency analysis rather than direct electrical contact through the water, eliminating the sticking issues caused by variable conductivity in different water conditions.
3Reliability
If sensor plates are used to detect bilge water levels, then the switch can reliably detect water presence, but the placement and configuration must be precise to meet design goals
Solution Approach 1:
The patent divides the sensing function into multiple sensor plates positioned at different locations. This segmentation provides redundancy and allows the system to detect water levels across a range of positions. The distributed arrangement reduces sensitivity to precise placement of any single plate, as the system can still function with reasonable placement variations.
Solution Approach 2:
The sensor plates serve multiple functions: they detect water presence, determine water level, and provide redundancy for reliable operation. This multi-functionality compensates for placement variations, as the system can interpret signals from multiple plates to accurately determine water conditions even if individual plate positions are not perfectly precise.
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 provides reliable activation and deactivation of bilge pumps, effectively managing bilge water levels regardless of soapy water or oil-water mixtures, ensuring safe and efficient operation by preventing sticking and conductivity-related issues.
Implementation Method 1
When both horizontal bare stainless steel sensor plates are covered, a bilge pump is activated. When both horizontal bare stainless steel sensor plates are uncovered, the bilge pump is deactivated.
Implementation Method 2
two sensor plates driven by a 20 KHz square wave
Data Source
AI summary
A liquid sensing switch comprising an upper sensor plate linked to electronics, a lower sensor plate linked to the electronics, and a ground linked to the electronics, wherein a pump is activated when a liquid level rises above a position of the lower sensor plate and above a position of the upper sensor plate, causing a current to pass between the two sensor plates.