Washing Machine Recirculation Pump Speed Control for Thermal Protection

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Solution Overview

Problem

Existing washing machine operations face challenges in achieving a good washing and rinsing effect without damaging the flooding device, as the volume flow of washing liquid affects both the efficacy and the mechanical components' temperature.

Innovation Solution

The method involves varying the volume flow of washing liquid by adjusting the speed of the circulation pump, with higher speeds for improved washing and rinsing effects and lower speeds to prevent overheating and damage, using temperature thresholds to control the pump's operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the volume flow of washing liquid is increased to improve washing and rinsing effects, then the washing and rinsing effectiveness is improved, but the circulation pump overheats and may be damaged

Engineering Contradiction:
Improvewashing and rinsing effectivenessVSAvoidcirculation pump durability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The circulation pump operates in periodic cycles, alternating between high-speed operation (for improved washing effect) and low-speed or idle operation (for cooling and preventing damage). The control device switches between these states based on operational phase and temperature conditions, implementing periodic action to resolve the contradiction between productivity and reliability.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The circulation pump speed is dynamically adjusted based on the washing phase and detected temperature. During washing phases, the pump operates at higher speeds for better washing effect, while during rinsing phases or when temperature thresholds are exceeded, the speed is reduced or stopped. This dynamic adaptation allows the system to optimize washing effectiveness while preventing pump overheating and damage.

Inventive Principle:
Principle #15Dynamics

2Productivity

If the circulation pump operates at high speed continuously, then the washing and rinsing effect is maximized, but the pump temperature increases and may cause damage

Engineering Contradiction:
Improvewashing effect intensityVSAvoidcirculation pump temperature
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

A temperature sensor continuously monitors the circulation pump temperature and provides feedback to the control device. Based on this feedback and the current washing phase, the control device adjusts the pump speed accordingly - maintaining high speed when temperature is acceptable for optimal washing effect, and reducing or stopping the pump when temperature thresholds are approached to prevent damage.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system changes the operational parameters (speed and temperature thresholds) of the circulation pump based on the washing phase and real-time temperature conditions. During washing phases, higher speeds are permitted for better washing effect, while during rinsing phases or when temperature exceeds predefined thresholds, the speed parameter is reduced or set to zero, allowing the pump to cool down and preventing thermal damage.

Inventive Principle:
Principle #35Parameter changes

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 ensures an effective washing and rinsing effect while preventing mechanical damage to the circulation pump by alternating between high and low volume flows based on temperature, maintaining optimal performance and safety.

Implementation Method 1

a flood device with a flood pump and a flood line... washing liquid is conveyed by means of the flooding pump from a first area of the tub through the flooding line into a second area of the tub

Methodology Applied
Scientific EffectPump: Pump

Implementation Method 2

the stressed mechanical components of the flooding device heat up and may be damaged... the mixing of the laundry with washing liquid also depends on the volume flow of washing liquid conveyed through the flooding device. If the volume flow is high, the stressed mechanical components of the flooding device heat up

Methodology Applied
Scientific EffectMechanical heating: Viscous Heating

Data Source

PatentEP2762631B1Method for operating a washing machine with recirculation device
Publication Date: 2016.04.06 MIELE & CO KG
  • EP2762631B1 patent drawingFigure 1
  • EP2762631B1 patent drawingFigure 2

AI summary

The invention relates to a method for operating a washing machine (1) with a tub (2) for holding washing liquid (3) for treating laundry (8) and a circulation device (11) with a circulation pump (11a) and a circulation line (11b). , comprising the implementation of a washing program with a washing phase and at least one rinsing phase, the circulation device (11) being activated at least during one of the washing or rinsing phases in such a way that washing liquid (3) is pumped out of a first area of ​​the tub ( 2) is conveyed through the bypass line (11b) into a second area of ​​the tub (2). A volume flow of the conveyed washing liquid (3) is varied. The invention also relates to a washing machine (1) with a circulation device (11) which has a circulation pump (11a) with variable speed.