Self-calibrating automatic controller to determine end of cycle and track dryer cycle efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing clothes dryers face challenges in accurately determining the endpoint of the drying cycle due to variations in air inlet temperature and sensor drift, and moisture sensors can be damaged by contact with dryer contents.
Innovation Solution
A controller that monitors temperature differences between incoming and outgoing air, or drum contents temperature, to determine the moisture level and weight of clothes, allowing for precise determination of the drying cycle endpoint and optional self-calibration for increased accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single temperature sensor on the exhaust outlet is used to determine drying cycle endpoint, then the sensing method is simple, but the accuracy is affected by air inlet temperature variations and sensor drift
Solution Approach 1:
The patent divides the temperature sensing function into multiple sensors: one sensor monitors exhaust temperature while another sensor monitors inlet air temperature. This segmentation allows the system to compensate for inlet temperature variations by comparing the differential between inlet and exhaust temperatures, thereby maintaining measurement precision without significantly increasing system complexity.
Solution Approach 2:
The system implements feedback by continuously monitoring the temperature differential between inlet and exhaust air, and using this information to adjust the drying cycle endpoint determination. The controller uses the temperature differential feedback to compensate for sensor drift and inlet temperature variations, improving endpoint detection accuracy over time.
2Measurement precision
If a moisture sensor with metal contacts inside the dryer drum is used to sense endpoint, then the sensor can detect moisture in clothes, but the contacts can fail due to contact with dryer contents
Solution Approach 1:
The patent extracts the moisture sensing function from direct contact with dryer contents by using indirect moisture detection through temperature differential measurement. Instead of placing metal contacts inside the drum that touch clothes, the system measures moisture content by monitoring the temperature difference between inlet and exhaust air, which changes as moisture evaporates from clothes. This eliminates the reliability issue of contacts failing due to contact with dryer contents.
Solution Approach 2:
The system uses air temperature differential as an intermediary to indirectly measure moisture content in clothes. Rather than directly contacting clothes with sensor contacts, the system measures how the evaporation of moisture from clothes affects the temperature of exhaust air relative to inlet air. This intermediary measurement method maintains moisture sensing capability while eliminating direct contact between sensors and dryer contents.
3Duration of action of stationary object
If temperature sensors are used to monitor drying cycle, then sensor drift occurs over time, but the system can implement self-calibration to maintain accuracy
Solution Approach 1:
The patent implements self-service through automatic self-calibration functionality. The system periodically performs self-calibration by establishing a baseline temperature differential relationship between inlet and exhaust sensors under known conditions, and uses this baseline to compensate for sensor drift during operation. This allows the system to maintain measurement precision automatically over the sensor's operational lifespan without requiring manual calibration or replacement.
Solution Approach 2:
The system performs preliminary calibration actions during manufacturing or initial operation to establish baseline temperature differential characteristics. This preliminary calibration data is stored and used as a reference for ongoing operation, allowing the system to maintain accuracy by comparing current measurements against the pre-established baseline, thereby compensating for sensor drift before it significantly affects 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 solution provides accurate and reliable endpoint detection for clothes dryers, reducing sensor-related issues and maintaining long-term accuracy, while also tracking energy efficiency and alerting users to deviations.
Implementation Method 1
the controller monitors the changing temperature of the dryer exhaust air compared to the incoming air to determine when a sufficient level of moisture has been removed from the clothes
Implementation Method 2
The changing temperature of the dryer exhaust air, drum temperature, or drum contents temperature, compared to the incoming air is used to determine the initial weight of the clothes and the weight of the clothes at a later time in the cycle (the weight is reduced as water evaporates)
Data Source
AI summary
An apparatus and method for controlling the drying cycle in a clothes dryer. The dryer controller measures differences between air inlet temperature and temperature of an air outlet, drum, and/or drum contents, from which it first estimates water weight of original drum contents based on changes in this temperature differential over a first period of time. A first dryness threshold is later reached when the amount of remaining water estimated by the temperature difference profiling reaches a threshold. A cooling cycle is then performed, followed by an estimation of remaining drying cycle time from estimating remaining water based on temperature differentials. The heater is then switched back on for the remaining time, after which a cooling cycle is preferably performed before ending the dryer cycle.