Washing Machine Drum Control Using Motor Current Variation

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Solution Overview

Problem

Existing washing machines lack a reliable method to detect the behavior of laundry items in the drum, such as sliding or falling, which can lead to inefficiencies and mechanical issues like vibration and noise, without requiring additional costly sensors.

Innovation Solution

A method that monitors and records the motor current and rotational position of the drum, calculates the coefficient of variation from the motor current curve, and compares it to stored values to determine the behavior of laundry items, allowing for adjustments in temperature, duration, and rotational speed for optimal washing processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If additional sensors are installed to detect laundry behavior, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:

Improvedetection accuracy of laundry behaviorVSAvoidhardware complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The drive motor performs dual functions: driving the drum and serving as a sensor for detecting laundry behavior through monitoring its own current consumption. The control unit analyzes current variations during drum rotation to determine laundry distribution and behavior patterns, eliminating the need for separate detection sensors.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The drive motor is utilized for multiple purposes: mechanical driving of the drum and electrical sensing of laundry behavior. By monitoring the motor current characteristics during operation, the system extracts information about laundry distribution, sliding, and falling patterns without requiring dedicated sensing components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If motor current is monitored continuously, then measurement precision is improved, but use of energy increases

Engineering Contradiction:

Improvedetection accuracy of laundry behaviorVSAvoidenergy consumption for monitoring

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

Instead of continuous monitoring, the system performs periodic measurements during specific drum rotation phases. The control unit divides revolutions into rotation sections and collects current data at intervals, particularly during phases where laundry behavior indicators are most pronounced, reducing overall energy consumption while maintaining detection accuracy.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system monitors motor current with higher precision during critical rotation sections where laundry behavior is most evident, rather than maintaining uniform high-precision monitoring throughout all operations. This selective monitoring approach optimizes energy usage by concentrating measurement resources when they provide maximum diagnostic value.

Inventive Principle:

Principle #16Partial or excessive action

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 enables secure and reliable detection of laundry behavior without additional hardware, optimizing washing processes and preventing mechanical damage by ensuring even distribution and appropriate rotational speeds.

Implementation Method 1

a drive motor (16) is provided to rotate the drum (14) in the receptacle (13)

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 2

The power supply (32) is also designed to monitor a motor current that is supplied to the drive motor (16)

Methodology Applied

Scientific EffectElectrical current measurement: Ohmmeter

Data Source

PatentUS20240271347A1Method for operating a washing machine and washing machine

Publication Date: 2024.08.15 E G O ELEKTRO GERAETEBAU GMBH

AI summary

In a method for operating a washing machine with a drum, a drive motor for the drum, a power supply for the drive motor and a washing machine control monitoring and detecting the motor current by means of the power supply, the following steps are performed where the motor current is constantly monitored while the drum rotates for at least three full revolutions. A full revolution of the drum is divided into three rotation sections of equal size, and the motor current is monitored and recorded for each of the rotation sections. An envelope curve of this motor current is calculated, and therefrom the standard deviation is calculated. The standard deviation is divided by the mean value of the envelope curve to determine the coefficient of variation for each rotation section. By comparing the determined coefficient of variation for each rotation section with stored values for the coefficient of variation, the behaviour of the laundry items is determined as to whether laundry items slide down the drum inner wall, fall from the drum inner wall or rotate together with the drum. From this behaviour, parameters are determined for a further operation of the washing machine with regard to the treatment of the laundry items.