Bread Maker Lid Assembly with Heat Reflection to Balance Thermal Dose

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Solution Overview

Problem

Existing automatic bread makers face challenges in producing bread with a hard texture, as a powerful heater can cause uneven baking, leading to burnt surfaces and dryness, while prolonged heating at lower temperatures may result in dry bread.

Innovation Solution

The automatic bread maker incorporates a lid assembly with a thermal insulation plate and an inner lid of higher heat reflectivity, along with an outer air layer and a steam cylinder, to enhance heat retention and balance the thermal dose distribution, ensuring even heating and preventing burning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a more powerful heater is used to increase thermal dose for hard texture bread, then the thermal dose to bread dough is increased, but the side and bottom surfaces of bread dough in contact with the kneading container are burned

Engineering Contradiction:
Improvethermal doseVSAvoidburning of bread dough surfaces
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by providing heat-reflecting surfaces (aluminum foil or mirrored finish) specifically on the inner lid and heating chamber walls, while the bottom heater continues to provide strong heating. This creates different thermal characteristics in different locations: the top and sides reflect heat back onto the bread, while the bottom provides direct heating, achieving balanced thermal dose distribution without burning any single surface.

Inventive Principle:
Principle #3Local quality

2Object-affected harmful factors

If heating is continued for a long time at a temperature that does not burn the side and bottom surfaces of the dough, then burning is avoided, but the entire bread dough is dried

Engineering Contradiction:
Improveburning preventionVSAvoidmoisture loss from bread dough
Core Design Contradiction:
Object-affected harmful factorsVSLoss of substance

Solution Approach 1:

The heat-reflecting surfaces enable continuous effective heating by reflecting thermal radiation back onto the bread dough multiple times. This continuous thermal action ensures thorough cooking and moisture retention throughout the extended heating period, preventing the bread from drying out while avoiding burning through balanced heat distribution.

Inventive Principle:
Principle #20Continuity of useful 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 configuration effectively produces bread with desirable hardness by increasing the heat reflectivity and retention, balancing the thermal dose supplied to the top and bottom surfaces, resulting in improved texture and preventing dryness.

Implementation Method 1

an inner lid having heat reflectivity higher than heat reflectivity of the thermal insulation plate and disposed inside the thermal insulation plate

Methodology Applied
Scientific EffectHeat reflection: Reflection

Implementation Method 2

a thermal insulation plate having outside dimensions larger than the kneading container in a planar view and disposed inside the outer lid

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 3

a heater disposed at a lower part of the heating chamber for heating the kneading container

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP3616520B1Automatic bread maker
Publication Date: 2023.11.08 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
  • EP3616520B1 patent drawingFigure 1
  • EP3616520B1 patent drawingFigure 2
  • EP3616520B1 patent drawingFigure 3

AI summary

An automatic bread maker according to the present disclosure includes a body; a heater case with a bottomed cylindrical shape; a kneading container; a heater; a kneading paddle; a drive unit; and a lid assembly. The heater case is disposed inside the body to define a heating chamber. The kneading container is disposed inside the heating chamber to accommodate ingredients. The heater is disposed at a lower part of the heating chamber to heat the kneading container. The kneading paddle stirs ingredients by rotating inside the kneading container. The drive unit rotates the kneading paddle. The lid assembly includes an outer lid exposed outside, a thermal insulation plate disposed inside the outer lid, and an inner lid disposed inside the thermal insulation plate, and covers the top opening of the heater case. The thermal insulation plate has outside dimensions larger than the kneading container in a planar view. The inner lid has heat reflectivity higher than that of the thermal insulation plate.