Washing Machine Foam Detection Using Temperature Increasing Speed

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Solution Overview

Problem

Existing laundry washing machines face challenges in detecting foam at an early stage of the washing cycle, leading to inefficient washing, detergent residue, and pump obstruction, with existing solutions being complex, costly, and unreliable.

Innovation Solution

A method that determines the temperature increasing speed of the washing liquid in the washing tub to detect foam, using a threshold value correlated to the quantity of water and heating device power dissipation, allowing for early foam detection and reduction actions during the washing cycle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a foam sensor is realized integral with a temperature sensor, then foam detection capability is improved, but device complexity and manufacturing costs increase

Engineering Contradiction:
Improvefoam detection capabilityVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The temperature sensor is designed to serve dual purposes: measuring washing liquid temperature for heating control and detecting foam presence through temperature increasing speed measurement. This multi-functional approach eliminates the need for a separate foam sensor, reducing device complexity while maintaining foam detection capability

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention changes the measurement parameter from static temperature to dynamic temperature increasing speed. By monitoring how quickly the temperature rises during the heating phase, the system can detect foam presence without requiring additional sensors or complex hardware modifications

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If foam detection is performed during balancing phase and spinning phase, then foam detection capability is improved, but washing efficiency deteriorates due to late detection

Engineering Contradiction:
Improvefoam detection capabilityVSAvoidwashing efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The system performs foam detection during the heating phase, which occurs early in the washing cycle before the balancing and spinning phases. This preliminary detection allows the control unit to identify foam presence early and adjust washing parameters proactively, preventing foam-related problems rather than reacting to them later

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The control unit continuously monitors temperature increasing speed during heating and uses this feedback to detect foam presence. Based on this real-time feedback, the system can adjust washing parameters dynamically to maintain optimal washing efficiency while managing foam conditions

Inventive Principle:
Principle #23Feedback

3Device complexity

If temperature increasing speed is used for foam detection, then device complexity is reduced, but measurement precision may deteriorate due to temperature fluctuations

Engineering Contradiction:
Improvedevice complexityVSAvoidfoam detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The invention transitions from static temperature measurement to dynamic temperature increasing speed measurement. By capturing the rate of change rather than a fixed value, the system becomes sensitive to foam's insulating effect on heat transfer, improving detection accuracy while using simple existing hardware

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system measures temperature at multiple time points during the heating phase to calculate temperature increasing speed. This periodic measurement approach allows the control unit to distinguish between normal temperature variations and foam-induced temperature changes, maintaining measurement precision

Inventive Principle:
Principle #19Periodic 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

Enables reliable and efficient foam detection at an early stage, reducing detergent residue and pump noise, with a simpler and more cost-effective design compared to existing systems.

Implementation Method 1

heating said washing liquid

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

detecting the washing liquid temperature in the washing tub and/or in the draining region thereof

Methodology Applied
Scientific EffectTemperature detection:

Data Source

PatentEP3235939B1Method for the detection of foam in a laundry washing machine
Publication Date: 2021.06.09 ELECTROLUX APPLIANCES
  • EP3235939B1 patent drawingFigure 1
  • EP3235939B1 patent drawingFigure 2
  • EP3235939B1 patent drawingFigure 3~3A

AI summary

The present invention relates to a method for operating a laundry washing machine (1; 200) having washing tub (3) containing a washing drum (4) and a heating device (20) for heating liquid in the washing tub (3). The method comprises the steps of: introducing a quantity of water and a quantity of detergent in the washing tub (3) to form a washing liquid; heating the washing liquid; determining the temperature increasing speed (TS); comparing the determined temperature increasing speed (TS) with a threshold value (TV) and if the determined temperature increasing speed (TS) is above the threshold value (TV) establishing the presence of foam.