Dishwasher Steam Rinsing for Residue-Free Drying

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Solution Overview

Problem

Conventional dishwashers lack an effective method to enhance cleaning efficiency while maintaining energy efficiency, particularly in the rinsing and drying phases.

Innovation Solution

Incorporating a steam generator that applies steam during the rinsing phase, where water condenses on dishes without leaving residues and provides efficient heat for drying, combined with a reduced pump flow rate to enhance heat transfer and prevent overheating, along with the option to use rinse aid for improved drying.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If steam is generated by heating water in the sump during the rinsing phase, then cleaning effect and drying efficiency are improved, but energy consumption increases

Engineering Contradiction:
Improvedrying efficiencyVSAvoidenergy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent utilizes the phase transition of water from liquid to steam during the rinsing phase. The steam generator heats water to produce steam, which then condenses on the dishes during drying, releasing latent heat directly to the dishes. This phase transition mechanism improves drying efficiency by 14% while managing energy consumption through direct heat transfer.

Inventive Principle:
Principle #36Phase transitions

Solution Approach 2:

The patent converts the typically wasted heat from the steam generation process into a beneficial drying mechanism. The steam that would otherwise be lost is directed to condense on the dishes, transforming what could be considered energy waste into useful drying heat, thereby improving overall energy utilization.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Temperature

If the pump operates at reduced flow rate during steam generation, then heat transfer is enhanced and overheating is prevented, but water circulation efficiency decreases

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidwater circulation efficiency
Core Design Contradiction:
TemperatureVSProductivity

Solution Approach 1:

The patent dynamically adjusts the pump flow rate based on the operational phase. During steam generation, the pump operates at reduced flow rate to enhance heat transfer and prevent overheating. During other phases, the pump returns to normal operation for efficient water circulation. This dynamic adjustment resolves the contradiction between heat transfer efficiency and water circulation efficiency.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements periodic variation in pump operation - reducing flow rate during steam generation phases and maintaining normal flow rate during other phases. This periodic action allows the system to optimize heat transfer when needed while preserving overall water circulation efficiency across the complete wash cycle.

Inventive Principle:
Principle #19Periodic action

3Manufacturing precision

If water is sprayed onto dishes during the entire rinsing phase, then cleaning is maintained, but steam generation and heat transfer are reduced

Engineering Contradiction:
Improvecleaning qualityVSAvoidsteam generation efficiency
Core Design Contradiction:
Manufacturing precisionVSTemperature

Solution Approach 1:

The patent segments the rinsing phase into distinct sub-phases: one where water is sprayed onto dishes for cleaning, and another where steam is generated for drying. This segmentation allows the system to prioritize steam generation and heat transfer during specific intervals while maintaining cleaning quality through targeted water application in other intervals.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs periodic switching between water spraying and steam generation during the rinsing phase. Water spraying is applied periodically to maintain cleaning quality, while steam generation is applied periodically to maximize heat transfer and drying efficiency. This periodic alternation resolves the contradiction between maintaining cleaning quality and optimizing steam generation.

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

Improves drying efficiency by 14% and reduces energy consumption by 140 Wh, while ensuring effective cleaning and residue-free drying.

Implementation Method 1

the water in the sump of the dishwasher and/or in the line system between the sump and the spray means of the dishwasher is heated to generate steam

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

The water condensing directly on the dishes has practically no impurities, so that it dries without leaving any residue. In addition, the condensation process allows heat to be supplied to the dishes

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 3

the pump of the dishwasher is operated in at least part of the rinsing phase with a reduced flow rate, during which the water emerging from the spray means does not impinge on the dishes, but flows directly through the tub to the sump. This increases the water surface and thus the heat transfer

Methodology Applied
Scientific EffectHeat transfer: Convection

Data Source

PatentEP1738677B1Dishwasher with steam generator and method of its operation
Publication Date: 2008.08.06 V-ZUG AG
  • EP1738677B1 patent drawingFigure 1

AI summary

The dishwasher has a tub (2) for accommodating dishes to be cleaned, and a steam generator (13) for applying steam in the tub. A controller (14) cleans the dishes in a main washing phase with cleaning medium, and sets up the dishes for an unstained drying in a clear washing phase. The controller is designed such that the dishes are charged with the steam from the steam generator in the clear washing phase, so that the dishes are clearly washed by water condensed from the steam. An independent claim is also included for a method of operating a dishwasher.