Surface Cleaner Fluid Level Sensing for Foam Overflow Prevention
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Solution Overview
Problem
Existing surface cleaning devices face challenges in efficiently managing fluid levels during the cleaning process, leading to potential overflow and damage due to the lack of effective fluid level sensing systems, particularly in environments with debris and foam.
Innovation Solution
A surface cleaning device equipped with a fluid level sensing system that includes multiple probes and a controller to detect liquid and foam levels, using high-frequency signals and self-capacitive sensing, along with an accelerometer to estimate tank fill volume and prevent overfill conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fluid level sensing methods are used, then the device structure remains simple, but the device cannot accurately detect fluid levels in environments with debris and foam, leading to overflow and damage
Solution Approach 1:
The patent replaces mechanical float-based level sensing with electronic self-capacitive sensing probes that measure fluid level through capacitance changes. This electronic substitution enables accurate detection through foam and debris layers that would block mechanical sensors, resolving the contradiction between reliability and simplicity by using a more sophisticated but functionally superior sensing mechanism.
Solution Approach 2:
The patent introduces high-frequency electrical signals as an intermediary medium to detect fluid levels. These signals penetrate foam and debris to reach the fluid interface, allowing indirect measurement of fluid level without direct contact with obstructing materials. This intermediary approach maintains sensing accuracy while avoiding the mechanical complexity of physical probes that must navigate through debris.
2Reliability
If no fluid level sensing system is used, then the device structure remains simple, but the device cannot prevent overflow and potential damage
Solution Approach 1:
The patent implements a feedback control system where self-capacitive sensors continuously monitor fluid levels and provide real-time data to a controller. When the fluid reaches a predetermined level, the controller automatically activates a drain pump to remove excess fluid, preventing overflow. This closed-loop feedback mechanism provides reliable overflow protection while maintaining reasonable system complexity through automated control.
Solution Approach 2:
The patent performs preliminary detection of fluid levels using self-capacitive sensing before overflow occurs. The system proactively identifies approaching fluid levels and triggers preventive drainage actions, rather than reacting after overflow has begun. This preliminary action approach ensures reliability by preventing damage before it occurs while using a moderately complex predictive control system.
3Measurement precision
If simple level detection is used, then the device complexity remains low, but the device cannot accurately distinguish between liquid and foam levels
Solution Approach 1:
The patent uses periodic high-frequency electrical signals to probe the fluid interface. By analyzing the temporal characteristics of signal reflection and capacitance changes at different frequencies, the system distinguishes between liquid and foam levels. This periodic measurement approach achieves precise differentiation through signal analysis rather than mechanical distinction, balancing measurement precision with acceptable sensing mechanism complexity.
Solution Approach 2:
The patent exploits changes in electrical parameters (capacitance, impedance, signal reflection) that occur at liquid-foam interfaces versus foam-air interfaces. By monitoring these parameter variations, the system precisely identifies distinct fluid levels without requiring mechanically different sensors for each fluid type. This parameter-based differentiation achieves high measurement precision while using a unified sensing mechanism of moderate complexity.
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 system effectively prevents overflow by accurately detecting fluid and foam levels, de-energizing components or alerting the user, thereby protecting the device and ensuring efficient operation.
Implementation Method 1
A surface cleaning device equipped with a fluid level sensing system that includes multiple probes and a controller to detect liquid and foam levels, using high-frequency signals and self-capacitive sensing
Implementation Method 2
along with an accelerometer to estimate tank fill volume
Data Source
AI summary
An apparatus for cleaning a surface includes a liquid delivery system for storing cleaning liquid and delivering the cleaning liquid to the surface to be cleaned, a fluid recovery system and a control system. The control system includes a controller that is coupled to a sensing assembly. Methods of operating the same include sensing foam or liquid with the sensing assembly.