Solid State Oven Cooling via Differential Pressure Air Circulation

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Solution Overview

Problem

Conventional microwave ovens are limited in cooking performance due to indiscriminate and uncontrollable energy application, which hinders efficient cooking and browning of food, and require redesigning the oven structure to integrate controllable RF and convection energy sources effectively.

Innovation Solution

An oven design incorporating a solid-state RF heating system with an advanced air circulation system that uses a cooling fan to maintain differential pressures for efficient cooling of solid-state components, allowing for controlled RF energy application and improved cooking performance by combining RF and convection heating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If solid state electronic components are used to generate RF energy, then cooking control and performance are improved, but heat management and cooling requirements become more complex

Engineering Contradiction:
Improvecooking controlVSAvoidcooling system complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent combines the cooling function with the existing convection heating system by using the same fan and air circulation pathways to perform both heating and cooling operations. The fan serves dual purposes: circulating hot air for cooking and drawing cooling air through solid state components, thereby merging two separate system functions into one integrated system.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The air circulation system is designed to perform multiple functions: it provides convection heating during normal operation and switches to cooling mode when solid state components require thermal management. The same fan, air pathways, and control system handle both heating and cooling tasks, making the system universal and multi-functional.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If a cooling system is added to the oven, then solid state components can be effectively cooled, but the internal spaces may accumulate dust and become contaminated

Engineering Contradiction:
Improvecomponent cooling effectivenessVSAvoiddust accumulation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the cooling air intake and exhaust pathways from the food cooking chamber by routing them through dedicated pathways that bypass the internal cooking spaces. Cooling air is drawn from external sources or from areas separate from the food chamber, and cooled air is exhausted through dedicated outlets, preventing dust accumulation in sensitive electronic components.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces separate air pathways and potentially filters as intermediary elements between the external environment and the solid state components. These intermediaries prevent direct contact between dust-laden air and sensitive electronics while still providing effective cooling through controlled air flow paths.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Loss of time

If microwave cooking is used to speed up cooking, then cooking time is reduced, but browning capability and cooking quality deteriorate

Engineering Contradiction:
Improvecooking timeVSAvoidcooking quality
Core Design Contradiction:
Loss of timeVSManufacturing precision

Solution Approach 1:

The patent enables continuous and coordinated application of both microwave RF energy and convection heat throughout the cooking process. Rather than using microwave alone followed by separate browning steps, the system continuously applies both heating mechanisms simultaneously or in coordinated sequences, maintaining useful cooking action throughout and achieving both speed and quality.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The patent changes the parameters of RF energy delivery by using solid state components that provide variable power levels, frequencies, and pulse patterns compared to traditional magnetron-based microwaves. This allows precise control of energy delivery to optimize both cooking speed and browning quality by adjusting parameters such as duty cycle, power level, and frequency modulation.

Inventive Principle:
Principle #35Parameter changes

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 oven achieves quick and uniform cooking with enhanced control over RF energy, enabling better browning and maintaining clean internal spaces by efficiently managing heat and preventing dust accumulation in sensitive areas.

Implementation Method 1

The cooling fan isolates the inlet cavity from the attic region to maintain the inlet cavity at a pressure below ambient pressure to draw cooling air into the inlet cavity via an inlet array, and to maintain the attic region at a pressure above ambient pressure to discharge air that has cooled the solid state electronic components

Methodology Applied
Scientific EffectPressure differential: Pressure Gradient

Implementation Method 2

air circulation system configured to provide air for cooling the solid state electronic components

Methodology Applied
Scientific EffectConvection cooling: Convection

Data Source

PatentEP3549393B1Apparatus and system for solid state oven electronics cooling
Publication Date: 2021.09.29 ILLINOIS TOOL WORKS INC
  • EP3549393B1 patent drawingFigure 1
  • EP3549393B1 patent drawingFigure 2
  • EP3549393B1 patent drawingFigure 3

AI summary

An air circulation system for an oven includes an inlet cavity, an attic region and a cooling fan. The oven includes a cooking chamber configured to receive a food product and an RF heating system configured to provide RF energy into the cooking chamber using solid state electronic components. The air circulation system is configured to provide air for cooling the solid state electronic components. The inlet cavity is disposed below the cooking chamber. The attic region is disposed above the cooking chamber and housing the solid state electronic components. The cooling fan isolates the inlet cavity from the attic region to maintain the inlet cavity at a pressure below ambient pressure to draw cooling air into the inlet cavity via an inlet array, and to maintain the attic region at a pressure above ambient pressure to discharge air that has cooled the solid state electronic components from an oven body of the oven.