Airflow Duct Geometry for Quiet, Faster Convection Cooking

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Solution Overview

Problem

Existing fan-assisted cooking appliances are noisy and require long cooking times due to turbulent air flow, which leads to energy losses and inefficiencies.

Innovation Solution

The cooking appliance features a ventilation duct with a geometrically limited cross-section to reduce turbulence, achieving laminar flow through fin-shaped heating means and a progressive reduction in section, eliminating the need for additional components to achieve silent operation and increased heating efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a conventional ventilation duct is used in fan-assisted cooking appliances, then air flow is generated to cook food, but turbulence occurs causing noisy operation and energy losses

Engineering Contradiction:
ImprovenoiseVSAvoidcooking time
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent changes the geometric parameters of the ventilation duct by progressively reducing its cross-sectional area along the flow direction. This parameter change transforms the turbulent flow into laminar flow, eliminating noise and reducing energy losses while maintaining cooking effectiveness.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs curved transition sections instead of abrupt changes in the duct geometry. The curved progressive reduction in section allows smooth flow transformation, preventing flow separation and turbulence, thereby achieving silent operation without compromising cooking performance.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Object-affected harmful factors

If additional components are added to reduce turbulence in the ventilation duct, then noise is reduced, but device complexity increases

Engineering Contradiction:
ImprovenoiseVSAvoidduct structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the turbulence reduction function into the duct structure itself through progressive geometric reduction. Instead of adding separate turbulence reduction components, the duct wall geometry is designed to inherently guide the flow smoothly, combining structure and function in a single element.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The ventilation duct structure serves dual purposes: it channels the air flow and simultaneously reduces turbulence through its progressive geometric design. The structure self-regulates the flow characteristics without requiring external control mechanisms or additional components.

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

The solution results in a silent operation and faster cooking times by minimizing energy losses and enhancing heating efficiency, while maintaining a portable and versatile domestic appliance design.

Implementation Method 1

the ventilation duct is arranged to reduce turbulence in the ventilation duct. In other words, the ventilation duct is arranged to obtain laminar flow

Methodology Applied
Scientific EffectLaminar flow: Laminar Flow

Implementation Method 2

the at least two fins being arranged opposite each other to separate, in said at least one section, the airflow into at least three air streams

Methodology Applied
Scientific EffectFlow separation: Flow Separation

Implementation Method 3

a heating circuit by ventilation comprising a ventilation duct arranged to channel and direct a flow of hot air onto the food to be cooked and/or to warm up

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 4

a progressive reduction in section arranged to progressively limit said geometric dimension of the air flow channeled along it. The progressive reduction according to this implementation makes it possible to restore speed to the air flow or to re-pressurize it

Methodology Applied
Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentEP2956038B1Appliance for cooking by air flow
Publication Date: 2018.06.06 SEB SA
  • EP2956038B1 patent drawingFigure 1~2

AI summary

The invention relates to an appliance for cooking and/or reheating food, which includes: a housing having a cooking vessel arranged such as to receive the food to be cooked and/or reheated, and a circuit for heating by ventilation including an air duct arranged such as to channel and direct a flow of hot air onto the food to be cooked and/or reheated, characterised in that the air duct has at least one cross-section in which a geometric size of the channelled air flow is limited such as to reduce a turbulence of the air flow flowing downstream from said at least one section of the air duct.