Microwave feed-in device on a microwave oven

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Solution Overview

Problem

Microwave ovens fail to achieve homogeneous heating due to non-uniform distribution of electromagnetic fields, resulting in 'hot' and 'cold' spots within the cooking chamber.

Innovation Solution

A coupling element with multiple arms, acting as a power distributor, splits the electromagnetic field into multiple waveguides, which open into the cooking chamber at strategically arranged feed points on angled walls, ensuring even energy distribution by controlling constructive and destructive superpositions of field strengths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single waveguide and coupling element are used to transmit electromagnetic field from microwave transmitter to cooking chamber, then the device structure is simple, but the electromagnetic field distribution in the cooking chamber is non-uniform resulting in hot and cold spots

Engineering Contradiction:
Improvetransmission device structureVSAvoidtemperature distribution uniformity
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The patent divides the single transmission path into multiple waveguides (at least three) that open at different locations on the cooking chamber walls. Each waveguide transmits electromagnetic energy to a specific region, segmenting the heating function across multiple channels to achieve more uniform field distribution throughout the cooking chamber.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent positions feed points at specific locations on different walls of the cooking chamber (including lateral walls) to create locally optimized field distribution. By strategically placing waveguide openings at different positions, each region of the cooking chamber receives appropriate electromagnetic energy, addressing local heating requirements.

Inventive Principle:
Principle #3Local quality

2Temperature

If mechanical disruptive elements are added to homogenize field distribution, then temperature uniformity improves, but device complexity and moving parts increase

Engineering Contradiction:
Improvetemperature distribution uniformityVSAvoiddevice structure
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent replaces mechanical field-disrupting elements (such as rotating mode stirrers or fans) with a static multi-waveguide transmission system. Instead of using moving mechanical parts to redistribute energy, the invention uses multiple fixed waveguides positioned at different locations to achieve homogeneous heating through spatial distribution of feed points.

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

3Temperature

If multiple feed points are provided on angled walls, then electromagnetic wave superposition is controlled to reduce hot and cold zones, but the transmission device becomes more complex

Engineering Contradiction:
Improvetemperature distribution uniformityVSAvoidtransmission device structure
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent combines multiple waveguides into a unified transmission device structure that integrates the power distributor and multiple waveguide channels. This merging approach achieves controlled electromagnetic wave superposition at strategically positioned feed points while maintaining structural coherence, reducing hot and cold zones through coordinated multi-point feeding.

Inventive Principle:
Principle #5Merging (Combining)

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 design significantly reduces the formation of hot and cold zones, providing a more uniform heating experience by ensuring that electromagnetic waves either add up constructively or not cancel out, leading to a more even temperature distribution within the food.

Implementation Method 1

The electromagnetic alternating field is fed into the coupling element and divided with its help into several waveguides, so that it can be conducted into the cooking chamber in several different ways

Methodology Applied
Scientific EffectElectromagnetic field distribution: Electromagnetic Induction

Implementation Method 2

Inside the cooking chamber, the electromagnetic waves spread out in the direction of their emission at the feed points and are reflected several times by the walls

Methodology Applied
Scientific EffectElectromagnetic wave reflection: Reflection

Implementation Method 3

Standing waves occurring in the cooking chamber are superimposed destructively or constructively. Hot or cold spots remain.

Methodology Applied
Scientific EffectWave superposition: Interference

Data Source

PatentEP3448121B1Microwave feed-in device on a microwave oven
Publication Date: 2020.12.23 VORWERK & CO INTERHOLDING GMBH
  • EP3448121B1 patent drawingFigure 1
  • EP3448121B1 patent drawingFigure 2~3
  • EP3448121B1 patent drawingFigure 4~5

AI summary

The invention relates to a device and a method for feeding an alternating electromagnetic field generated by a microwave transmitter (1, 2) into a cooking chamber (14) of a microwave oven, wherein the alternating electromagnetic field is transmitted in a power flow direction from the microwave transmitter (1, 2) to several feed points (11, 12, 13) of the cooking chamber (14) by means of a transmission device, at which the power generated by the microwave transmitter (1, 2) is fed into the cooking chamber (14), wherein the transmission device has at least one waveguide (8, 9, 10) and a coupling element (3) coupled to the waveguide (8, 9, 10).A fork-shaped coupling element (3) ensures that the microwaves fed into the coupling element (3) are distributed onto several waveguides (8, 9, 10) which are fed into the cooking chamber (14) at different feed points (11, 12, 13), so that the electromagnetic waves propagating in the cooking chamber (14) interfere less constructively or destructively and the formation of cold or hot spots in the food being cooked is reduced.