Passive Resonant Temperature Probe for Oven Monitoring

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing wireless temperature measurement systems for ovens face challenges such as position-dependent measurements, limited operational temperature ranges, and errors due to near-field effects and thermal insulation, which hinder accurate and continuous temperature monitoring of oven loads.

Innovation Solution

A measurement system with interrogation antennas and passively operated temperature probes featuring resonators with distinct temperature coefficients and similar electrical equivalent circuit diagrams, allowing for position-independent temperature measurement by stabilizing the difference frequency of resonances, reducing errors from antenna near-field effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If wireless temperature probes with active electronic systems and batteries are used, then temperature measurement is possible, but the system fails at temperatures above 125°C due to thermal damage to electronic components and energy sources

Engineering Contradiction:

Improvemeasurement temperature rangeVSAvoidsystem reliability at high temperature

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent replaces active electronic temperature sensing systems with passive resonant frequency-based temperature sensors. The temperature measurement is achieved through mechanical resonance of a cantilever beam structure that changes its resonant frequency with temperature, eliminating the need for batteries and active electronics that fail at high temperatures.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses the temperature-dependent change in resonant frequency of the passive sensor as the measurement parameter. The resonant frequency of the cantilever beam varies with temperature according to the relationship f(T) = f0 * sqrt(1 - α(T - T0)), where α is a temperature coefficient, enabling temperature measurement without active electronics.

Inventive Principle:

Principle #35Parameter changes

2Temperature

If thermal insulation is applied to protect active electronic systems and energy sources, then the system can function at higher temperatures for limited periods, but the system cannot operate continuously and requires large component sizes

Engineering Contradiction:

Improveoperating temperatureVSAvoidcontinuous operation capability

Core Design Contradiction:

TemperatureVSDuration of action of stationary object

Solution Approach 1:

The patent eliminates the need for thermal insulation by replacing active electronic systems with a passive mechanical resonator that inherently withstands high temperatures. The passive cantilever beam sensor has no batteries or sensitive electronics that require thermal protection, enabling continuous operation at elevated temperatures.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If the difference of frequency dependence of storage of vibration energy is not evaluated, then the measurement system is simpler, but the measurement accuracy becomes position-dependent due to transmission path effects

Engineering Contradiction:

Improvetemperature measurement accuracyVSAvoidevaluation complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses the resonant frequency of the passive cantilever beam as an intermediary parameter that directly correlates with temperature. By measuring the resonant frequency shift caused by temperature changes in the beam, the system achieves accurate temperature measurement without complex evaluation of transmission path effects or multiple sensor comparisons.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 system achieves high accuracy and continuous temperature monitoring of oven loads with reduced measurement errors across varying temperatures, enabling precise control of heating processes.

Implementation Method 1

the temperature sensor has at least a first resonance element and a second resonance element... the resonant frequency of the first resonance element and the resonant frequency of the second resonance element

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

the temperature sensor has at least a first resonance element and a second resonance element... evaluation unit is designed to determine the temperature of the load of the oven from the difference between the resonant frequency of the first resonance element and the resonant frequency of the second resonance element

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS8930160B2Measurement system for the wireless position-independent measurement of the temperature

Publication Date: 2015.01.06 VECTRON INT GMBH & CO KG

AI summary

The invention relates to a measurement system for the wireless and position-independent measurement of the temperature of the load of an oven with high accuracy using passive temperature probes. The measurement system for the wireless measurement of the temperature of food or workpieces in ovens has an interrogation unit located outside the oven chamber, one or more interrogation antennas located in the oven chamber and at least one passively operated temperature probe with a probe antenna and at least one temperature sensor designed as a resonator, said temperature probe being freely movable within the oven, characterized in that the temperature sensor has at least two resonances with different temperature coefficients of frequency, wherein the electrical equivalent circuit diagrams of the resonance elements differ only slightly from each other.