Dryer Drum Conductivity Sensing for Accurate Moisture Cutoff
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Solution Overview
Problem
Current laundry drying technologies face challenges in accurately determining the residual moisture content of laundry, often resulting in over-drying or under-drying, which affects appliance efficiency and consumer satisfaction.
Innovation Solution
A laundry treating appliance equipped with a rotatable drum and dual conductivity sensors positioned at the rear and front of the treating chamber, where the drum rotates at a predetermined speed to ensure laundry tumbles over the sensors, allowing the controller to select the signal with the greater number of conductivity readings to determine the drying cycle duration based on moisture content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single conductivity sensor is used to determine moisture content, then the device complexity is reduced, but the measurement precision deteriorates resulting in inaccurate determination of desired moisture range
Solution Approach 1:
The treating chamber is segmented into multiple zones (front and rear) with conductivity sensors distributed throughout. This segmentation allows the system to capture moisture content variations at different locations, improving overall measurement precision while maintaining manageable device complexity through modular sensor placement.
Solution Approach 2:
The patent transitions from a single-point moisture measurement to a spatially distributed measurement system by placing sensors at multiple locations within the treating chamber. This dimensional expansion from one point to multiple points in space enables more accurate determination of overall moisture content by accounting for spatial variations.
2Productivity
If the drum rotates at high speed to improve drying efficiency, then the productivity increases, but the laundry may not adequately contact the sensors resulting in poor measurement reliability
Solution Approach 1:
Multiple conductivity sensors are distributed at different angular positions around the drum's path. This segmentation ensures that regardless of the drum's rotational speed or laundry load characteristics, at least some sensors will reliably contact the laundry and generate valid conductivity signals for moisture determination.
Solution Approach 2:
Sensors are strategically positioned at specific locations (front and rear of treating chamber) where laundry is most likely to pass during tumbling. This local optimization of sensor placement ensures reliable contact and signal generation while allowing the drum to rotate at speeds that maximize drying efficiency.
3Measurement precision
If the drying cycle is extended to ensure thorough drying, then the measurement precision of moisture content improves, but the loss of time increases and energy is wasted
Solution Approach 1:
Multiple conductivity sensors continuously monitor moisture content throughout the drying cycle, providing preliminary and ongoing measurements rather than relying on a single end-point check. This enables the controller to detect when the desired moisture range is approached and terminate the cycle promptly, preventing both under-drying and over-drying.
Solution Approach 2:
The system implements continuous feedback monitoring using distributed conductivity sensors that report moisture content at multiple locations. The controller uses this real-time feedback to dynamically adjust or terminate the drying cycle when the desired moisture range (2-4%) is achieved, optimizing both precision and time efficiency.
4Measurement precision
If multiple conductivity sensors are deployed throughout the treating chamber, then the measurement precision of moisture content improves, but the device complexity increases
Solution Approach 1:
The treating chamber is divided into discrete sensor zones (front and rear positions) with a limited number of conductivity sensors placed at strategic locations. This segmentation approach achieves adequate measurement precision by sampling key regions without requiring a dense sensor network, thus controlling device complexity.
Solution Approach 2:
Each conductivity sensor serves multiple functions: it measures moisture content, provides spatial information about moisture distribution, and enables cycle termination decisions. This multi-functionality reduces the need for additional specialized sensors, maintaining device complexity at acceptable levels while achieving high measurement precision.
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 enhances the accuracy of determining the end of the drying cycle, ensuring laundry is dried to a desired moisture range (2-4%), improving appliance efficiency and user satisfaction by providing more precise control over the drying process.
Implementation Method 1
a first conductivity sensor located at the rear of the treating chamber, a second conductivity sensor located at the front of the treating chamber
Data Source
AI summary
An apparatus and method towards a laundry treating appliance for drying laundry comprising a rotatable drum at least partially defining a treating chamber and having a front and a rear where at least one conductivity sensor is located within the treating chamber, and a motor rotating the drum tumbles laundry within the treating chamber to ensure contact of the laundry with the conductivity sensor.