Magnetron Temperature Sensing for No-Load Heating Control

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Solution Overview

Problem

Conventional high-frequency heating equipment struggles to accurately detect and control no-load states due to temperature sensor malfunctions caused by heat convection, conduction, and radiation, leading to potential thermal runaway and resource wastage from incorrect shutdowns.

Innovation Solution

A temperature sensor mounted with a mounting bracket that presses against the cooling fins, positioning the sensor to sense the magnetron's anode temperature directly, reducing dispersion factors and ensuring timely detection of temperature rises.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the temperature sensor is mounted on the outside cooling fin to sense the magnetron's temperature, then the sensor is protected from direct heat exposure, but the sensor response is delayed and temperature detection accuracy is reduced due to heat convection and conduction through the cooling fins

Engineering Contradiction:
Improvetemperature detection accuracyVSAvoidtemperature sensing response time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent introduces a heat-conducting member (such as a metal plate or thermal conduit) as an intermediary between the magnetron anode and the temperature sensor. This intermediary directly contacts the hot anode and rapidly conducts heat to the sensor, eliminating the need to wait for heat to traverse the cooling fins. The intermediary member accelerates thermal signal transmission while the sensor remains positioned in a cooler, more stable environment.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The temperature sensing system is divided into two functional segments: a heat detection zone (the anode surface) and a sensor measurement zone (the sensor location). The heat-conducting member bridges these segments, allowing the sensor to indirectly measure anode temperature without being exposed to extreme heat. This segmentation enables fast response while protecting the sensor.

Inventive Principle:
Principle #1Segmentation

2Loss of time

If the temperature sensor is positioned close to the magnetron anode to improve detection speed, then the response time is reduced, but the sensor is exposed to excessive heat causing thermal runaway and potential breakdown

Engineering Contradiction:
Improvetemperature sensing response timeVSAvoidsensor operational stability
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The heat-conducting member serves as a thermal intermediary that decouples the sensor from direct heat exposure. It conducts heat from the anode to the sensor while maintaining a temperature gradient that keeps the sensor within its operational range. This intermediary allows the sensor to be positioned closer to the heat source without suffering thermal damage.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The temperature sensor is extracted from the high-temperature zone near the anode and placed in a cooler zone, while the heat-conducting member extracts the thermal signal from the anode and delivers it to the sensor location. This extraction allows the sensor to operate in a stable thermal environment while still detecting anode temperature changes rapidly.

Inventive Principle:
Principle #2Taking out (Extraction)

3Temperature

If the cooling fan operates at high speed to cool the magnetron effectively, then the cooling performance is improved, but the airflow causes heat convection that interferes with the temperature sensor's accurate measurement

Engineering Contradiction:
Improvemagnetron cooling efficiencyVSAvoidtemperature sensor measurement accuracy
Core Design Contradiction:
TemperatureVSMeasurement precision

Solution Approach 1:

The heat-conducting member acts as a thermal intermediary that is shielded from the cooling airflow. It conducts heat from the anode to the sensor through solid conduction, bypassing the convective cooling air. This allows the cooling fan to operate at high speed for effective magnetron cooling while the temperature measurement remains accurate and unaffected by airflow convection.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces reliance on air convection for temperature measurement with solid thermal conduction through the heat-conducting member. Instead of using the cooling airflow to transport thermal information to the sensor (which causes measurement interference), the system uses direct thermal conduction through a solid medium, substituting a more reliable heat transfer mechanism for the measurement function.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

Accurate differentiation between no-load and light-load states prevents thermal runaway and resin component damage, reducing resource wastage and ensuring stable equipment performance.

Implementation Method 1

the heat conduction to cooling fins 3B

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

cooling fan 7 for cooling magnetron 3 and power supply 6

Methodology Applied
Scientific EffectForced convection: Forced Convection

Implementation Method 3

magnetron 3 oscillates electromagnetic waves, thereby heating object to be heated 5

Methodology Applied
Scientific EffectElectromagnetic radiation: Electromagnetic Induction

Implementation Method 4

anode 3A is heated, and this heat travels to cooling fins 3B, thereby raising a temperature of temperature sensor 10

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Data Source

PatentEP2378204B1High-frequency heating equipment
Publication Date: 2015.05.06 PANASONIC HOLDINGS CORP
  • EP2378204B1 patent drawingFigure 1
  • EP2378204B1 patent drawingFigure 2~3
  • EP2378204B1 patent drawingFigure 4~5

AI summary

A high-frequency heating equipment includes temperature sensor (21) that is mounted with mounting bracket (22) such that temperature sensor (21) can be pressed by a lateral face of cooling fins and an end of temperature sensor (21) points to an anode of magnetron (3). This structure allows positively preventing magnetron (3) from falling into a thermal runaway which invites a breakdown of magnetron (3), and allows determining in a reliable manner whether the operation is a no-load running or a light-load running. The high-frequency heating equipment thus achieves stable performance.