Microwave Guide Structure for Cooking Cavity
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Solution Overview
Problem
Existing microwave cooking appliances face challenges in efficiently transmitting microwave power while minimizing heat transfer to the microwave source and maintaining a gas-tight seal, leading to potential damage and malfunctions.
Innovation Solution
The design incorporates a microwave guide structure with two sections, one having a rectangular cross-section and the other a circular cross-section, with a slot antenna and inner conductor for efficient microwave radiation, and uses dielectric materials for impedance matching and thermal insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If microwaves are transmitted via coaxial cables, then microwave power can be delivered to the cooking zone, but only low microwave power can be transmitted and heat transfer to the microwave source occurs
Solution Approach 1:
The microwave transmission system is segmented into multiple components: a waveguide structure with first and second sections, a coaxial connector, and a mode mixer. This segmentation allows each component to perform its specific function optimally - the waveguide transmits high power with minimal heat transfer, the coaxial connector provides impedance matching, and the mode mixer distributes microwaves uniformly throughout the cooking zone.
Solution Approach 2:
The waveguide structure acts as an intermediary between the microwave source and the cooking zone. It provides a dedicated microwave transmission path that isolates the microwave source from direct thermal exposure while efficiently delivering high power microwaves to the cooking area through its specialized geometry and material properties.
2Productivity
If a waveguide with large contact area is used, then microwave transmission is efficient, but heat conduction to the microwave source increases
Solution Approach 1:
The waveguide structure employs local quality by having different cross-sectional shapes in different sections - a rectangular cross-section in the first section for optimal microwave coupling and a circular cross-section in the second section for reduced heat conduction. This localized variation in geometry allows each section to optimize for its specific function while maintaining overall transmission efficiency.
Solution Approach 2:
The transition from a rectangular to a circular cross-section in the waveguide utilizes the geometric properties of curved surfaces. The circular geometry in the second section provides more uniform stress distribution and reduced thermal contact area compared to rectangular shapes, thereby decreasing heat conduction to the microwave source while maintaining microwave transmission efficiency.
3Loss of energy
If the waveguide opening is made small, then heat transfer is reduced, but the structure becomes more complex to seal gas-tightly
Solution Approach 1:
Instead of making the waveguide opening small to reduce heat transfer, the invention inverts the approach by using a relatively large opening but designing the waveguide structure itself to minimize thermal contact. The waveguide's specialized geometry and support structure allow for a large opening that facilitates easy sealing while the waveguide components are configured to have minimal thermal contact area with the microwave source.
4Ease of manufacture
If coaxial cables are used for microwave transmission, then the system is simple to implement, but microwave power transmission is limited
Solution Approach 1:
The invention merges the advantages of coaxial cables with waveguide technology. The system uses a coaxial connector for the interface section where simplicity is needed, while transitioning to a waveguide structure for the main transmission path where high power capability is required. This combination allows the system to maintain ease of manufacture at the connection interface while achieving high power transmission in the cooking zone.
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 reduces heat transfer, facilitates a gas-tight seal, and allows for higher microwave power transmission, improving appliance efficiency and reliability.
Implementation Method 1
a microwave guide structure (24, 25; 28; 48; 73; 88) for guiding microwaves from at least one microwave source (22, 23) up to at least one opening in a wall or a wall part (8; 78; 93) of the interior (10, 11)
Implementation Method 2
at least one element (47; 70; 84; 97) for radiating the microwaves into the interior (10th ,11)
Implementation Method 3
with a dielectric material (41, 71, 83, 96) with a permittivity which differs from the permittivity of air, filled
Implementation Method 4
to insulate a microwave generator relatively well from the interior climate in order to avoid damage and/or malfunctions of the microwave generator
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The device has a microwave guiding structure (48) for guiding microwaves from a microwave source to an opening in a wall or wall part of a cooking space. The structure has outer, electrically conductive and firm walls (54, 59) and microwave emitting elements e.g. antennas (47, 70) in the cooking space. The guiding structure has a rectangular hollow conductor (49) and a section (50), which has a circular cross-section that is different from a cross-section of the hollow conductor. The microwave emitting element is arranged at an end of the section. An independent claim is also included for a method for supplying microwaves into a cooking space of a cooking device.