Washing Machine Drum Torque Sensing for Load Weight Detection
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Solution Overview
Problem
Existing washing machines face challenges in determining the weight of laundry accurately and efficiently, leading to potential motor imbalances, noise, and alarms due to uneven loading, which complicates the operation and requires costly modifications.
Innovation Solution
A method that involves rotating the drum at a given speed before a washing or drying program to calculate torque and unbalance values, comparing them to thresholds, and adjusting program parameters or calculating the laundry weight based on these conditions to prevent imbalances and ensure proper operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If initial tumbling or spinning of the drum is performed to determine load at the beginning of the washing program, then load determination is achieved, but motor alarms and hits between drum components may occur
Solution Approach 1:
The patent performs a preliminary detection phase by rotating the drum at a low speed (5-15 rpm) before the main washing program to measure torque values. This preliminary action allows load determination without the high-speed tumbling that causes motor alarms and component hits, thus resolving the contradiction between measurement precision and reliability.
2Measurement precision
If weighting scale is used to determine laundry weight, then accurate weight measurement is achieved, but production costs increase noticeably
Solution Approach 1:
The patent replaces the mechanical weighting scale with an electrical measurement system that uses the motor's torque characteristics. By measuring the electrical torque values during low-speed drum rotation and comparing them to reference values, the system determines laundry weight without requiring additional mechanical weighing components, thus reducing production costs while maintaining measurement precision.
3Loss of time
If drum rotation is performed quickly to determine load weight, then determination time is reduced, but measurement accuracy decreases
Solution Approach 1:
The patent performs a brief preliminary detection phase at low speed (5-15 rpm) to obtain initial torque measurements for load determination. This short-duration preliminary action provides sufficient accuracy for weight determination without requiring lengthy high-speed rotation, thus reducing determination time while maintaining acceptable 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 method allows for quick and accurate determination of laundry weight, preventing motor imbalances and alarms, ensuring efficient and effective washing or drying operations without significant cost increases.
Implementation Method 1
calculating a value associated with a torque and/or an unbalance of the drum during the rotation at the first speed
Data Source
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AI summary
The present invention relates to a method for operation of a laundry apparatus, said laundry apparatus including a drum which is rotatably mounted in a casing, the method including: ∘ selecting a washing or drying program among a plurality of washing or drying programs; ∘ rotating the drum for a given first time interval and given first speed before beginning of said washing or drying program; ∘ calculating a value associated with a torque and/or an unbalance of the drum during the rotation at the first speed; ∘ comparing the value with a first and/or second threshold; ∘ if said value associated with a torque and/or an unbalance is above the first and/or second threshold, then the method further includes: • emitting a command to change a parameter of said selected washing or drying program; or ∘ if said value associated with a torque and/or an unbalance is below or equal to the first and/or second threshold, then the method further includes: • calculating a first weight of said laundry before beginning of said selected washing or drying program.