Microwave Trap Slot Segmentation for Lower Door Leakage
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Solution Overview
Problem
Conventional microwave traps in household appliances, particularly those with bent sheet-metal components and parallel bending slots, fail to achieve satisfactory impermeability to microwaves, resulting in higher leakage rates due to frequency deviations and evanescent field coupling with adjacent metal components.
Innovation Solution
Introducing webs into the bending slots of the microwave trap's main bending edge, which aligns with a row of teeth, reduces frequency deviations and suppresses evanescent field coupling, thereby enhancing microwave impermeability without complex dimensioning adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bending slots are used in the microwave trap, then the manufacturing process is simple, but the microwave impermeability is insufficient due to frequency deviations and evanescent field coupling
Solution Approach 1:
The bending slot is divided into multiple sections by introducing webs, creating a segmented structure. This segmentation disrupts the continuous path for evanescent field coupling and reduces frequency deviations, thereby improving microwave impermeability without requiring complex dimensional adjustments to the entire trap structure
Solution Approach 2:
Webs are strategically positioned at specific locations within the bending slot to locally modify the electromagnetic field distribution. This local modification suppresses evanescent field coupling at critical points while maintaining the overall simplicity of the trap structure
2Manufacturing precision
If the microwave trap is designed with simple bending slots, then the manufacturing is easier, but the effective frequency deviates from the operating frequency
Solution Approach 1:
The webs are pre-positioned within the bending slots during manufacturing to establish the correct effective frequency before the trap is installed. This preliminary configuration ensures proper frequency alignment without requiring complex post-installation adjustments or sophisticated manufacturing processes
3Shape
If bending slots are added to the microwave trap, then the shaping is enabled, but evanescent field coupling with adjacent metal components increases
Solution Approach 1:
The webs within the bending slots convert the potentially harmful evanescent field coupling into a beneficial structure by disrupting the continuous field path. The segmented slot structure allows the trap to maintain its necessary bent shape while the webs prevent harmful electromagnetic coupling with adjacent metal components
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 significantly reduces microwave leakage by aligning the effective frequency with the operating frequency and minimizing evanescent field coupling, allowing for simpler design modifications and reduced metal component placement around the trap.
Implementation Method 1
The basic forms of the shielding devices in household microwave appliances in accordance with the basic principle of a lambda quarter-wave trap have long been known
Implementation Method 2
The microwaves are generated by means of a microwave generator 108 and are directed into the cooking chamber, e.g. via a rotary antenna 109. The 'operating frequency' of the microwaves generated by the microwave generator 108 can be e.g. 2.45 GHz±20 MHz
Data Source
AI summary
A household microwave appliance includes a microwave treatment chamber having a loading opening, a door for closing the loading opening of the microwave treatment chamber, and a microwave trap configured to prevent microwaves escaping when the door is closed. The microwave trap is a bent sheet-metal component with a main bending edge, which is adjoined by a row of teeth at a distance. The microwave trap includes a row of bending slots in the main bending edge, with at least one of the bending slot being interrupted by a web to define slot sections.