RF Choke Resonant Elements for Microwave Oven Leakage Control
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Solution Overview
Problem
Conventional microwave ovens are limited in cooking speed and inability to brown food, and combination ovens with multiple heating sources face challenges in controlling energy application and preventing RF leakage, which affects cooking performance and cleanliness.
Innovation Solution
An oven design incorporating controllable RF energy and convection heating with an improved RF choke and interface structure to maintain energy within the cooking chamber, using solid-state components for RF generation and a dual air circulation system for cooling and cleaning, while allowing for browning through heated airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional microwave cooking is used, then cooking speed is improved, but the ability to brown food and control energy application is lost
Solution Approach 1:
The heating function is segmented into two independent systems: RF heating elements for rapid internal heating and convection heating elements for surface browning. This allows selective activation of each heating mode to achieve both speed and browning capability without compromise
Solution Approach 2:
The oven employs dynamic control of heating elements through solid-state components that can be independently adjusted in intensity and duration. The controller enables flexible combination of RF and convection heating at varying power levels, providing precise control over the cooking process
2Productivity
If combination heating sources are employed, then cooking performance is improved, but RF leakage and cleanliness issues arise
Solution Approach 1:
An RF choke is introduced as an intermediary component at the door opening to block RF leakage while allowing air circulation. The choke creates an electromagnetic barrier that prevents RF energy from escaping the cooking chamber, eliminating the harmful effect without compromising the combination heating function
Solution Approach 2:
The RF choke is extracted as a separate, removable component that can be independently maintained and replaced. This isolation of the RF containment function allows the heating systems to operate effectively while the choke specifically addresses the RF leakage problem
3Reliability
If traditional RF containment structures are used, then RF leakage is prevented, but oven cleanliness and air circulation are compromised
Solution Approach 1:
The RF choke utilizes a mesh or perforated structure that acts as a flexible electromagnetic barrier. This thin-film approach maintains RF containment while allowing air to pass through freely, enabling proper air circulation for convection heating and making the oven easier to clean compared to solid traditional shields
4Ease of operation
If solid-state RF generation components are used, then control over RF energy is improved, but heat generation from components increases
Solution Approach 1:
Air circulation serves as a cooling intermediary that removes heat from solid-state RF components. The dual air circulation system directs airflow across component surfaces, dissipating generated heat and maintaining operational temperatures within safe limits while preserving the control advantages of solid-state technology
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
Enhances cooking performance by enabling quick and controlled cooking with browning capabilities while preventing RF leakage and ensuring oven cleanliness, improving operator experience and cooking results.
Implementation Method 1
a plurality of resonant elements formed in rows... configured to reflect the RF energy back into the cooking chamber
Implementation Method 2
a RF energy source configured to generate controllable RF energy into a cooking chamber
Implementation Method 3
a convection system... enabling browning of the food product by the convection system
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An RF choke for an oven having a door (104) movable between an open position and a closed position to interface with an opening defined in a cooking chamber (102) of the oven includes a base portion (410) and a plurality of resonant elements (420) formed in rows. The cooking chamber (102) is defined at least in part by a top wall (305), a bottom wall (310), a first sidewall and a second sidewall (315, 320). The RF choke (140) is disposed at a portion of the door (104) facing the cooking chamber (102) when the door (104) is in the closed position. The base portion (410) is a metallic sheet and is disposed in a first plane substantially parallel to a second plane in which the door (104) lies. The resonant elements (420) are folded out of the first plane toward the door (104) to define a top row of resonant elements (420), a bottom row of resonant elements, a first side row of resonant elements and a second side row of resonant elements, which are proximate to respective ones of the top wall, the bottom wall, the first sidewall and the second sidewall of the cooking chamber when the door is in the closed position. At least one of the rows is folded out of the first plane at a different angle relative to the first plane than other ones of the rows.