Compact Magnetron Filter Case Design for Noise Suppression
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Solution Overview
Problem
Conventional magnetrons for microwave ovens face challenges in reducing size while maintaining safety standards and minimizing noise, with existing designs struggling to predict size reduction impacts and often experiencing insulation failures and noise generation.
Innovation Solution
A magnetron design featuring a pair of choke coils with air-core and core type inductances connected in series, where one end of each choke coil is connected to cathode input conductors and the other end to capacitor terminals, with specific dimensions for the filter case, air-core inductance, and high-frequency absorbing member to maintain safety standards and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the filter case height is reduced to make the magnetron compact, then the size is reduced, but the safety standards cannot be satisfied
Solution Approach 1:
The patent reduces the filter case height in the vertical dimension (from conventional heights to 35-45mm) while compensating by optimizing horizontal dimensions and component layout. The choke coil outer diameter is controlled at 5.5-7.5mm and the high frequency absorbing member sectional area at 5-16mm², maintaining safety distances in horizontal planes while achieving compactness in the vertical dimension.
Solution Approach 2:
The patent specifies precise parameter ranges: filter case height of 35-45mm, choke coil outer diameter of 5.5-7.5mm, high frequency absorbing member sectional area of 5-16mm², and electrostatic capacity of 500-700pF. By optimizing these parameters within defined ranges, the design achieves both compact size and safety compliance simultaneously.
2Volume of moving object
If the choke coil size is reduced to make the magnetron compact, then the size is reduced, but noise is generated in the 400 MHz to 700 MHz frequency band
Solution Approach 1:
The patent controls the choke coil outer diameter within 5.5-7.5mm and the high frequency absorbing member sectional area within 5-16mm². By optimizing these dimensional parameters, the design suppresses noise in the 400-700MHz frequency band while maintaining compact size. The specific parameter ranges are determined to achieve the optimal balance between size reduction and noise suppression.
Solution Approach 2:
The patent employs a composite structure combining air-core type inductance with core type inductance containing high frequency absorbing members (ferrite cores). This composite choke coil design leverages the properties of both air-core and ferrite-core inductors to achieve compact dimensions while suppressing electromagnetic noise in the problematic frequency range.
3Volume of moving object
If the high frequency absorbing member size is reduced to make the magnetron compact, then the size is reduced, but the insulation failure risk increases
Solution Approach 1:
The patent specifies the high frequency absorbing member sectional area should be 5-16mm². This parameter range is optimized to maintain sufficient insulation reliability and prevent dielectric breakdown while achieving compact dimensions. The parameter ensures the ferrite core is large enough to prevent insulation failure but small enough to contribute to overall compactness.
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 design allows for a compact magnetron that satisfies safety standards and reduces noise in the 400 MHz to 700 MHz frequency band, achieving a size reduction while maintaining safety and noise suppression.
Implementation Method 1
a core type inductance having a bar-shaped high frequency absorbing member (ferrite core) 57 in a winding
Implementation Method 2
an air-core type inductance 55 and a core type inductance 56 having a bar-shaped high frequency absorbing member (ferrite core) 57 in a winding are connected in series
Data Source
AI summary
It is an object to provide a magnetron for a small-sized microwave oven which takes safety standards and a noise into consideration, in a magnetron 10 for a microwave oven, a pair of choke coils 16 and 17 are provided in a filter case 11, and a height H1 of the internal surface of the filter case 11 is set to be 35 to 45 mm, an outside diameter d3 of an air-core type inductance 25 is set to be 5.5 to 7.5 mm and a sectional area S of a high frequency absorbing member 27 is set to be 5 to 16 mm2. In the magnetron 10 for a microwave oven, an electrostatic capacity between capacitor terminals 15A and 15B and the filter case 11 is increased to be 500 to 700 pF.