Steam Generator Scale Control in Fabric Treatment Appliances

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Solution Overview

Problem

Scale and sludge formation in steam generators of fabric treatment appliances due to dissolved substances in household water leads to heat transfer and fluid flow issues, potentially causing premature heater failure.

Innovation Solution

Incorporating a method and structure for preventing and removing scale and sludge through a steam generator cleaning process, which includes filling the steam generation chamber with water, heating it to produce steam, and then using a controlled valve duty cycle to manage water flow, along with optional thermal shock to loosen and flush out deposits, and employing a filter in the water supply line to purify water before entering the steam generator.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If water from household water supply is used in the steam generator, then the steam generator can operate continuously, but scale and sludge form in the steam generation chamber

Engineering Contradiction:
Improvecontinuous operationVSAvoidscale and sludge formation
Core Design Contradiction:
Duration of action of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary actions by automatically filling the steam generation chamber with water before the heater operates, and subsequently draining water after steam generation. This preliminary and follow-up action prevents scale and sludge formation by ensuring water circulation and preventing stagnant water residue that would otherwise lead to deposit accumulation during continuous operation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The steam generator system performs self-cleaning through automatic water filling and draining operations. The controller automatically activates the water inlet valve to fill the chamber and then opens the drain valve to remove water, enabling the system to maintain itself without external intervention. This self-service mechanism prevents scale and sludge buildup while allowing continuous operation.

Inventive Principle:
Principle #25Self-service

2Reliability

If the steam generation chamber is cleaned frequently to remove scale and sludge, then heat transfer efficiency is maintained, but operation time is lost

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidcleaning time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs self-cleaning operations automatically without requiring manual intervention or stopping the appliance for extended periods. The controller automatically executes water filling and draining sequences that clean the steam generation chamber internally, maintaining heat transfer efficiency while minimizing operational disruption and time loss.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system implements periodic water filling and draining cycles to continuously prevent and remove scale and sludge deposits. By performing these cleaning actions at regular intervals during operation, the system maintains optimal heat transfer efficiency without requiring dedicated cleaning time, as the cleaning is integrated into the normal operational cycle.

Inventive Principle:
Principle #19Periodic action

3Object-affected harmful factors

If a filter is added to the water supply line to remove dissolved substances, then scale formation is prevented, but device complexity increases

Engineering Contradiction:
Improvescale formationVSAvoidwater treatment structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The system extracts and removes dissolved substances from the water supply by incorporating a filter in the water inlet line. This filter specifically targets calcium, magnesium, and other minerals that cause scale formation, separating them from the water before it enters the steam generation chamber. This extraction approach prevents scale formation without requiring complex water treatment systems.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The filter acts as an intermediary component between the household water supply and the steam generation chamber. It mediates the water quality by removing harmful dissolved substances while allowing clean water to pass through to the steam generator. This intermediary filter prevents scale formation without adding significant complexity to the overall system.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Effectively prevents and removes scale and sludge, maintaining efficient heat transfer and extending the lifespan of the steam generator by regularly cleaning the chamber and using filtered water to reduce mineral content.

Implementation Method 1

a heater embedded in the main body... The heater is turned on to heat the water in the steam generation chamber

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

heating it to produce steam

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 3

employing a filter in the water supply line to purify water before entering the steam generator

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Implementation Method 4

using a controlled valve duty cycle to manage water flow, along with optional thermal shock to loosen and flush out deposits

Methodology Applied
Scientific EffectThermal shock: Thermal Shock

Data Source

PatentEP1865099B1Prevention of scale and sludge in a steam generator of a fabric treatment appliance
Publication Date: 2010.01.20 WHIRLPOOL CORP
  • EP1865099B1 patent drawingFigure 1
  • EP1865099B1 patent drawingFigure 2
  • EP1865099B1 patent drawingFigure 3

AI summary

A fabric treatment appliance comprises a steam generator (60) having a housing with an inner surface (72) defining a chamber (74) and having a surface treatment that inhibits adherence of scale to the inner surface. In another embodiment, the fabric treatment appliance can include a water supply line (170) configured to supply water from a household water supply to the steam generator (60B) and a filter (190) fluidly coupled to the water supply line and configured to filter water supplied to the steam generator to thereby inhibit formation of scale and sludge.