Multi-Tuned Choke System for Wide Band RF Leakage Containment

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Solution Overview

Problem

Conventional RF choke systems in ovens are insufficient for preventing RF leakage across a wide range of frequencies, as they are typically tuned to a single frequency, leading to extensive leakage outside that frequency range.

Innovation Solution

A choke assembly comprising multiple tuned chokes arranged concentrically around the oven door, each configured to shield different predefined frequencies, effectively containing RF energy within the oven by combining with the door and cooking chamber walls when closed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single tuned choke is used to shield RF energy, then shielding effectiveness at that specific frequency is improved, but RF leakage at other frequencies increases

Engineering Contradiction:
Improveshielding effectivenessVSAvoidfrequency range coverage
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The choke assembly is segmented into multiple tuned chokes (first tuned choke, second tuned choke, etc.), each tuned to different frequencies. This segmentation allows each choke to specialize in blocking specific frequency ranges, collectively providing broad-spectrum RF shielding coverage that a single choke cannot achieve alone.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If multiple tuned chokes are used to cover wide frequency range, then RF leakage prevention across broad frequencies is improved, but device complexity increases

Engineering Contradiction:
Improvefrequency range coverageVSAvoidchoke assembly structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The tuned chokes are arranged in a nested configuration where inner chokes are positioned within the structure of outer chokes. This nesting approach allows multiple chokes to occupy overlapping spatial volumes, reducing the overall assembly footprint and simplifying the structural complexity compared to a side-by-side arrangement of multiple chokes.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The choke assembly is designed as a multi-functional unit where each tuned choke serves multiple purposes: blocking RF leakage at its specific frequency, contributing to the overall shielding structure, and working synergistically with other chokes. This multi-functionality reduces the need for additional separate components, thereby managing complexity.

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

3Volume of moving object

If concentric arrangement of multiple tuned chokes is used, then space utilization is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvespace utilizationVSAvoidassembly complexity
Core Design Contradiction:
Volume of moving objectVSEase of manufacture

Solution Approach 1:

The concentric arrangement of tuned chokes follows a nested doll principle where smaller chokes are positioned inside larger ones, maximizing space utilization. This configuration allows the chokes to share common mounting structures and alignment features, which can actually simplify manufacturing by reducing the number of separate mounting operations required compared to distributed arrangements.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 multi-tuned choke system significantly reduces RF leakage over a broad frequency range, enhancing the performance of ovens employing RF cooking by ensuring effective containment of RF energy, thereby improving cooking efficiency and safety.

Implementation Method 1

The choke assembly includes a plurality of tuned chokes, each of which is configured to shield relative to a different predefined frequency

Methodology Applied
Scientific EffectElectromagnetic resonance: Resonance

Data Source

PatentEP2820918B1Multiple choke system for containing wide frequency band RF leakage
Publication Date: 2017.09.27 ILLINOIS TOOL WORKS INC
  • EP2820918B1 patent drawingFigure 1
  • EP2820918B1 patent drawingFigure 2
  • EP2820918B1 patent drawingFigure 3

AI summary

An oven may include a radio frequency (RF) source, a cooking chamber into which RF energy is providable via the RF source, and a door that is configured to hingedly operate to alternately allow access to the cooking chamber and close the cooking chamber for cooking. The door may include a choke assembly disposed to seal a region between the door and a cooking chamber from RF leakage responsive to closure of the door. The choke assembly may include a plurality of tuned chokes, each of which is configured to shield relative to a different predefined frequency.