Toaster Intermittent Heating Control to Reduce Outer Surface Burning

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional toasters fail to achieve optimal heating of both the outer surfaces and innermost layers of toast, with short programs browning the outside but underheating the inside, while longer programs risk burning the outer surfaces.

Innovation Solution

A toaster with a control unit executing a main heating program comprising a series of activations and deactivations of the heating element, allowing heat to penetrate deeper into the food without burning the outer surfaces, along with a user interface to select between continuous and intermittent heating programs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the heating program duration is extended to heat the innermost layers of toast, then the inside heating is improved, but the outer surfaces get too hot or burn

Engineering Contradiction:
Improveinnermost layers heating temperatureVSAvoidouter surface burning
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The heating element operates in periodic cycles with multiple activation phases separated by deactivation phases. During activation phases, the heating element heats the toast; during deactivation phases, heat penetrates to innermost layers without additional external heat input. This periodic action allows controlled heat penetration to the center while preventing excessive outer surface temperature and burning.

Inventive Principle:
Principle #19Periodic action

2Object-affected harmful factors

If the heating program duration is shortened to prevent outer surface burning, then the outer surface browning is satisfactory, but the inside is underheated

Engineering Contradiction:
Improveouter surface burning preventionVSAvoidinnermost layers heating temperature
Core Design Contradiction:
Object-affected harmful factorsVSTemperature

Solution Approach 1:

The heating program uses periodic activation and deactivation phases. During brief activation phases, the outer surfaces are quickly browned; during subsequent deactivation phases, heat continues to penetrate to the innermost layers without additional external heat input. This allows adequate inner heating while limiting total external heat exposure time to prevent outer surface burning.

Inventive Principle:
Principle #19Periodic action

3Temperature

If continuous heating is applied to heat the food thoroughly, then the inside heating is improved, but the outer surfaces get excessively dry or burned

Engineering Contradiction:
Improvefood internal temperatureVSAvoidouter surface dryness and burning
Core Design Contradiction:
TemperatureVSObject-generated harmful factors

Solution Approach 1:

The heating element operates periodically with activation phases for heating and deactivation phases for heat penetration. During deactivation phases, no additional heat is applied to the outer surfaces, allowing them to cool slightly and preventing excessive dryness and burning, while heat continues to penetrate to the food interior during these intervals.

Inventive Principle:
Principle #19Periodic action

4Adaptability or versatility

If multiple heating programs are provided for different food types, then the versatility is improved, but the device complexity increases

Engineering Contradiction:
Improveheating program varietyVSAvoidcontrol unit complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The control unit implements a standardized periodic heating pattern with activation and deactivation phases that can be applied across multiple heating programs. This modular periodic approach allows the same fundamental heating mechanism to serve multiple food types and cooking requirements, achieving versatility without proportionally increasing device complexity.

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

This solution ensures even heating of both the outer surfaces and innermost layers of food, improving the quality of toasted products and preventing burning, while maintaining a simple and economical manufacturing structure.

Implementation Method 1

Heating elements are also associated with the heating compartments, typically consisting of electric resistors that, when run by electric current, transfer heat to the foods inserted in the heating compartments

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

Heating elements are also associated with the heating compartments, typically consisting of electric resistors that, when run by electric current, transfer heat to the foods inserted in the heating compartments

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP3079540B1Toaster and method for controlling said toaster
Publication Date: 2017.08.16 WHIRLPOOL EMEA SPA
  • EP3079540B1 patent drawingFigure 1

AI summary

A toaster comprising: at least one heating compartment (11, 12), in which the food to be heated (13, 14) is positioned; at least one heating element (21-24), associated with said at least one heating compartment (11, 12) and adapted to heat the food (13, 14) positioned in said at least one heating compartment (11, 12); a control unit (30), acting upon said at least one heating element (21-24) and configured for executing a main heating program comprising a succession of activations, separated by respective deactivations, of said at least one heating element (21-24).