Temperature measuring device with core temperature sensor

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Solution Overview

Problem

Existing core temperature sensors using NTC resistors face limitations in achieving high measurement accuracy and resolution across widely separated temperature ranges, necessitating either low accuracy across these ranges or the use of more expensive PTC resistors.

Innovation Solution

A core temperature sensor employing multiple NTC resistors with distinct resistance-temperature (R/T) characteristics, allowing selection based on predefined temperature ranges, ensuring high accuracy and resolution while maintaining cost-effectiveness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single NTC resistor is used for temperature measurement, then the device remains cost-effective, but high measurement accuracy and resolution can only be achieved within a relatively narrow temperature range

Engineering Contradiction:
Improvetemperature measurement accuracyVSAvoidtemperature range coverage
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The temperature measurement function is segmented into multiple NTC resistors, each optimized for a specific temperature range. The system divides the overall temperature measurement task into multiple specialized sub-tasks, where each NTC resistor handles a particular segment of the temperature spectrum, thereby achieving high precision across a wide range without requiring a single expensive component

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system dynamically selects which NTC resistor to use based on the current temperature range being measured. The control unit automatically switches between different NTC resistors as the temperature varies, ensuring that the optimal sensor for the current conditions is always active. This dynamic adaptation maintains high measurement accuracy across the entire temperature spectrum

Inventive Principle:
Principle #15Dynamics

2Measurement precision

If PTC resistors are used to achieve high measurement accuracy over a wider temperature range, then measurement precision improves, but the device cost increases considerably

Engineering Contradiction:
Improvetemperature measurement accuracyVSAvoiddevice cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The invention uses multiple inexpensive NTC resistors instead of a single expensive PTC resistor. Each NTC resistor is a cost-effective component that, when used in combination, provides the wide temperature range capability previously only achievable with costly PTC resistors. This approach maintains affordability while achieving the desired measurement performance

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The system creates a composite temperature sensing solution by combining multiple NTC resistors with different R/T characteristics. This composite approach leverages the strengths of each individual NTC resistor to create a system that matches or exceeds the performance of expensive single-component solutions like PTC resistors

Inventive Principle:
Principle #40Composite materials

3Adaptability or versatility

If multiple NTC resistors with different R/T characteristics are used, then the sensor can measure different temperature ranges with high accuracy, but the device complexity increases

Engineering Contradiction:
Improvetemperature range coverageVSAvoidsensor structure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Multiple NTC resistors are integrated into a single universal temperature sensing device that can handle various temperature ranges. The control unit provides a unified interface for temperature measurement across the entire range, making the complex multi-resistor system as easy to use as a simple single-resistor sensor while achieving superior versatility

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

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

Enables accurate temperature measurement across different ranges with cost-effective NTC resistors, expanding the sensor's applicability to various temperature scenarios, including both food core and appliance operating temperatures.

Implementation Method 1

The invention relates to a core temperature sensor (1) comprising an elongated measuring tube (2) with several NTC resistors

Methodology Applied
Scientific EffectNegative temperature coefficient (NTC): Thermistor

Data Source

PatentEP4189348B1Temperature measuring device with core temperature sensor
Publication Date: 2025.10.29 BSH HAUSGERATE GMBH
  • EP4189348B1 patent drawingFigure 1~2
  • EP4189348B1 patent drawingFigure 3
  • EP4189348B1 patent drawingFigure 4

AI summary

The invention relates to a core temperature sensor (1) having a longitudinal measuring tube (2) with multiple NTC resistors (NTC, NTC1a - NTC1d, NTC2). At least two of the NTC resistors (NTC1a - NTC1d, NTC2) have differing R/T characteristics (RT1, RT2). A temperature measuring device (1) has a core temperature sensor (1) and a data processing device (6), wherein the differing R/T characteristics (RT1, RT2) of the NTC resistors (NTC1a - NTC1d, NTC2) of the core temperature sensor (1) can be retrieved by the data processing device (6), and the temperature measuring device (1) is designed to: select one R/T characteristic (RT1, RT2) on the basis of a specified temperature target value (Tsoll), measure resistance values (R(t)) of at least one of the NTC resistors (NTC1a - NTC1d, NTC2) belonging to the selected R/T characteristic (RT1, RT2), and determine respective temperature values (T(t)) from the resistance values (R(t)) and the corresponding selected R/T characteristic (RT1, RT2). In particular, the invention can be advantageously used on domestic cooking devices, in particular baking ovens and cooking devices with a heatable support, such as grills, hot stones, etc.