Dishwasher Dual Heating Sequence for Gentle Rapid Water Heating

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Solution Overview

Problem

Dishwashers often subject sensitive items to excessive thermal stress during heating, particularly when using instantaneous water heaters, which can damage delicate items and prolong washing cycles.

Innovation Solution

A method for operating a dishwasher that uses a combination of a water heater for rapid heating to a higher temperature and an air heater for gentle initial heating to a lower temperature, integrated with a sorption drying system, allowing for energy-efficient and controlled temperature adjustments to reduce thermal loads on items.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If an instantaneous water heater is used to heat the liquid quickly, then the heating speed is improved, but the thermal stress on sensitive items increases

Engineering Contradiction:
Improveheating speedVSAvoidthermal stress on sensitive items
Core Design Contradiction:
SpeedVSObject-affected harmful factors

Solution Approach 1:

The heating process is divided into two distinct phases: a first phase using the air heater to gently heat the liquid and items to a low temperature, and a second phase using the water heater to rapidly heat the liquid to the final temperature. This segmentation allows different heating rates to be applied at different times, protecting sensitive items during initial heating while achieving quick overall heating.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The air heater is operated first to preliminarily heat the liquid and items to a low temperature before the water heater is activated. This preliminary action prepares the items for subsequent rapid heating by the water heater, reducing the thermal shock they would experience if heated directly from cold temperatures.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the liquid is heated to a high temperature directly, then the cleaning effectiveness is improved, but the program duration is extended

Engineering Contradiction:
Improvecleaning effectivenessVSAvoidprogram duration
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The heating process is segmented into two phases with different heating rates. The air heater phase establishes a baseline temperature, and the water heater phase rapidly achieves the target temperature. This segmentation optimizes the balance between heating time and cleaning effectiveness by using the most efficient heater for each phase.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system changes the heating parameters by switching between two different heating methods with different characteristics. The air heater provides gentle heating suitable for initial temperature rise, while the water heater provides intensive heating for rapid temperature achievement, optimizing both time and cleaning effectiveness.

Inventive Principle:
Principle #35Parameter changes

3Use of energy by moving object

If only a water heater is used for heating, then the heating efficiency is improved, but the thermal load on items increases

Engineering Contradiction:
Improveheating efficiencyVSAvoidthermal load on items
Core Design Contradiction:
Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The heating function is segmented between two different heating devices: the air heater handles the initial gentle heating phase, and the water heater handles the rapid heating phase. This segmentation allows each heater to operate in its optimal mode while protecting items from excessive thermal load.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The air heater acts as an intermediary between the cold initial state and the high-temperature final state. It provides a intermediate heating step that prepares items for the more intensive water heater operation, mediating the thermal transition to reduce shock to sensitive items.

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

This approach reduces thermal stress on items, shortens washing cycles, and ensures optimal cleaning by gently heating sensitive items to a low temperature before rapidly increasing to a higher temperature for effective cleaning, while also enhancing energy efficiency and desorption processes within the dishwasher.

Implementation Method 1

a water heater (WZ) for heating the liquid to a high temperature

Methodology Applied
Scientific EffectResistive heating: Joule Heating

Implementation Method 2

an air heater (HZ) for heating the air to a low temperature

Methodology Applied
Scientific EffectResistive heating: Joule Heating

Implementation Method 3

it is also able to expel liquid from a desiccant

Methodology Applied
Scientific EffectDesorption: Desorption

Data Source

PatentEP2352410B1Dishwasher and related method for heating the liquid thereof
Publication Date: 2015.09.02 BSH HAUSGERATE GMBH
  • EP2352410B1 patent drawingFigure 1
  • EP2352410B1 patent drawingFigure 2
  • EP2352410B1 patent drawingFigure 3

AI summary

The invention relates to a method for operating a dishwasher (GS), especially a household dishwasher, wherein a liquid is heated to an end temperature (T2) by a first heating means. According to the invention, a second heating means is used to heat the liquid to a temperature (T1, T1') that is lower than the end temperature (T2).