Steam Oven Thermal Load Control for Accurate Food Sensing

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Solution Overview

Problem

Existing automatic cooking ovens with steam generating systems face inaccuracies in determining optimal cooking parameters due to the dominance of steam in heat supply, leading to unreliable results in steam or combination cooking modes.

Innovation Solution

An automatic cooking oven with a control system that calculates thermal load based on food alone, using a steam control system to determine steam injection rates and power levels, ensuring accurate cooking parameters without requiring weight-related input, and incorporating a steam supply control to adjust steam generation dynamically.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If thermal load measurement is used to determine cooking parameters in steam ovens, then automation is improved, but measurement precision deteriorates because steam dominates the thermal load signal

Engineering Contradiction:
Improveautomated cooking controlVSAvoidfood amount detection accuracy
Core Design Contradiction:
Extent of automationVSMeasurement precision

Solution Approach 1:

The patent segments the total thermal load into two distinct components: steam-induced thermal load and food-induced thermal load. By measuring the temperature change rate and separating these components mathematically, the system can accurately determine the food amount despite steam dominating the overall thermal environment. This segmentation allows automated control while maintaining precise measurement of food parameters.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system implements feedback by continuously monitoring the temperature change rate during the cooking process and using this information to adjust cooking parameters. The control system measures the actual thermal load, compares it with expected values, and automatically adjusts power levels and cooking time to maintain optimal cooking conditions, thereby achieving both automation and measurement precision.

Inventive Principle:
Principle #23Feedback

2Reliability

If steam is used as the primary heat source, then cooking quality is improved through moisture retention, but control difficulty increases due to the dominance of steam in heat supply

Engineering Contradiction:
Improvecooking quality consistencyVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical control mechanisms with a mathematical model-based control system. Instead of using complex hardware to manage steam and heat distribution, the system uses temperature change rate measurements and algorithmic calculations to determine cooking parameters. This substitution simplifies the physical control mechanisms while maintaining reliable cooking quality through precise parameter control.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If automatic cooking control is implemented without weight input, then ease of operation is improved, but cooking parameter accuracy deteriorates

Engineering Contradiction:
Improveuser input requirementsVSAvoidcooking parameter determination accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The system implements self-service by automatically determining food amount and cooking parameters without requiring user input of weight or other food characteristics. The control system autonomously measures the temperature change rate, calculates the thermal load, and derives the food amount and optimal cooking parameters automatically. This eliminates the need for manual weight input while maintaining accurate cooking parameter determination through intelligent sensing and calculation.

Inventive Principle:
Principle #25Self-service

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 solution improves the accuracy of steam cooking operations by reliably determining cooking parameters, allowing for precise control of cooking time and power rates, even with small thermal loads, enhancing the overall cooking performance.

Implementation Method 1

a steam generating system for cooking food by steam only or in combination with conventional heating means

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

steam generating system

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 3

conventional heating means

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 4

convection or fan-forced dry-heat

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP2123981B1Automatic cooking oven comprising steam generating system
Publication Date: 2010.11.03 ELECTROLUX HOME PROD CORP NV
  • EP2123981B1 patent drawingFigure 1
  • EP2123981B1 patent drawingFigure 2~3

AI summary

An automatic cooking oven for automatic steam cooking of food is disclosed. Based on supplied user information a corresponding preprogrammed control program is selected. The control program is divided into cooking phases during which the thermal load represented by injected steam is determined, based on its mass. The thermal load of the total oven fill of steam and food is determined based on the heat response of the oven cavity to a power input. Then the thermal load represented by food is determined as the difference between the thermal load of the oven fill and the thermal load of steam. Cooking parameters related to the amount of food are then deduced from said food-related thermal load determination. A method of automatically steam cooking food is also provided.