Laundry Dryer Dryness Detection Under Variable Drum and Fan Speeds
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing laundry dryer systems inaccurately detect the end of a drying cycle due to variations in rotation speed and air stream fan speed, leading to premature termination of the cycle, as the conductometric system is calibrated for fixed speeds and is affected by changes in contact between electrodes and laundry at low speeds or when the air stream fan speed is modified.
Innovation Solution
The method involves varying the rotation speed of the laundry drum and air stream fan during the drying cycle, with the control unit adjusting these speeds based on the selected drying cycle, laundry amount, dryness level, and air stream temperature, while using specific impedance and conductivity threshold values to accurately determine the end of the cycle, ensuring the cycle is not prematurely stopped.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the rotation speed of the laundry drum is varied to optimize drying performance and reduce energy consumption, then energy efficiency improves, but the conductometric system produces inaccurate dryness level signals because it is calibrated for fixed rotation speeds
Solution Approach 1:
The patent applies dynamics by making the end cycle condition dynamic rather than fixed. The control unit adjusts the end cycle condition based on the actual rotation speed of the laundry drum detected during the drying cycle. This allows the system to accommodate varying rotation speeds while maintaining accurate dryness detection, resolving the contradiction between energy-efficient speed variation and measurement precision.
Solution Approach 2:
The patent changes the parameter of the end cycle condition based on rotation speed. Instead of using a fixed threshold, the system modifies the end cycle condition parameter according to the detected rotation speed, ensuring accurate dryness level detection across different operating speeds and eliminating false premature cycle terminations.
2Productivity
If the air stream fan speed is modified to improve drying performance, then drying efficiency increases, but the contact between electrodes and laundry changes causing false end cycle detections
Solution Approach 1:
The patent implements feedback by continuously detecting the air stream fan rotation speed and using this information to adjust the end cycle condition. The control unit monitors the actual fan speed and modifies the drying cycle termination criterion accordingly, ensuring reliable end cycle detection even when fan speed varies to optimize drying efficiency.
3Loss of energy
If the laundry drum is stopped for extended intervals to reduce energy consumption, then energy efficiency improves, but the conductometric system cannot accurately measure dryness level due to lack of electrode-laundry contact
Solution Approach 1:
The patent applies dynamics by making the end cycle condition adaptive to the actual operating conditions. When the laundry drum is stopped or rotates at low speed, the control unit detects this state and adjusts the end cycle condition accordingly, allowing accurate dryness measurement even during extended idle intervals while maintaining energy efficiency.
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 optimizes drying performance, reduces energy consumption, and prevents false detections of the end cycle condition by calibrating the end cycle condition checking system to the current rotation speed, thereby ensuring the cycle completes effectively.
Implementation Method 1
detecting an electric resistance and/or conductivity of the laundry during the drying cycle for estimating a dryness level of the laundry
Data Source
AI summary
A method is provided for controlling a drying cycle of a laundry dryer having a laundry drum and an air stream fan for circulating drying air through said laundry drum. The method includes the steps of: starting a drying cycle (14); performing the drying cycle (16); detecting an electric resistance and/or conductivity of the laundry during the drying cycle (16) for estimating a dryness level of the laundry; comparing the electric resistance and/or conductivity of the laundry with an end cycle condition (20; 28, 30; 36); and finishing the drying cycle (16), if the end cycle condition (20; 28, 30; 36) is fulfilled. The end cycle condition (20; 28, 30; 36) depends on the rotation speed (SD) of the laundry drum and/or on the rotation speed (SF) of the air stream fan.