Heating Device Substrate Recessed Sensor Temperature Control

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Solution Overview

Problem

Existing heating devices for household appliances face challenges in accurately measuring temperature on the usage side due to significant temperature differences between the heater and the usage side, leading to unreliable temperature regulation and reduced sensor lifespan.

Innovation Solution

A heating device design featuring a substrate with a recessed temperature sensor attached to the rear side, shielded from the medium, allowing for independent temperature measurement and improved response to temperature changes on the usage side, while maintaining protection and ease of cleaning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the temperature sensor is attached directly to the heater, then the temperature measurement is simple to implement, but the measurement accuracy deteriorates due to significant temperature differences between the heater and usage side

Engineering Contradiction:
Improveease of implementationVSAvoidtemperature measurement accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The substrate serves as an intermediary thermal element between the heater and the temperature sensor. The sensor measures the substrate temperature rather than directly contacting the heater, allowing accurate inference of usage side temperature through characteristic curves while being thermally coupled to the heating process.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The temperature sensor is extracted from direct contact with the heater and positioned on the substrate instead. This separation removes the sensor from the high-temperature, high-fluctuation environment of the heater while maintaining thermal coupling through the substrate for accurate measurement.

Inventive Principle:
Principle #2Taking out (Extraction)

2Extent of automation

If the temperature sensor is attached directly to the heater, then the temperature regulation can be implemented, but the sensor lifespan is reduced due to exposure to high temperatures and medium

Engineering Contradiction:
Improvetemperature regulation capabilityVSAvoidsensor lifespan
Core Design Contradiction:
Extent of automationVSReliability

Solution Approach 1:

The substrate acts as a protective intermediary that shields the temperature sensor from direct exposure to the harsh medium (food, lye, process air) and extreme thermal conditions. The sensor remains on the protected rear side while still measuring substrate temperature for regulation purposes.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The substrate provides beforehand protection against thermal shock and chemical exposure. By positioning the sensor on the substrate rather than directly on the heater, the system pre-shields the sensor from damaging conditions before they can affect sensor lifespan.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Device complexity

If the temperature sensor is attached to the heater surface, then the structure is simple, but the temperature fluctuations and maximum temperature values are higher

Engineering Contradiction:
Improvestructural simplicityVSAvoidtemperature stability
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The substrate serves as a thermal buffer that smooths out temperature fluctuations and reduces peak temperature values. The sensor measures the stabilized substrate temperature rather than the more variable heater temperature, achieving better thermal stability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the measurement parameter from direct heater temperature to substrate temperature, which has inherently lower fluctuations and maximum values due to the substrate's thermal mass and heat distribution properties.

Inventive Principle:
Principle #35Parameter changes

4Measurement precision

If the temperature sensor is attached on the usage side, then the measurement is direct, but the cleaning becomes more difficult and the structure is less compact

Engineering Contradiction:
Improvedirect temperature measurementVSAvoidease of cleaning
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

Instead of placing the sensor on the usage side where it would directly measure temperature but hinder cleaning, the sensor is inverted to the rear side of the substrate. The substrate itself becomes the measurement target, providing indirect but accurate measurement while maintaining easy cleaning access.

Inventive Principle:
Principle #13The other way round (Inversion)

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

This design enhances measurement accuracy and response time to temperature changes, extends sensor lifespan, and reduces maximum temperature values and fluctuations, enabling more precise temperature regulation and easier cleaning.

Implementation Method 1

at least one panel heater arranged on the rear side of the substrate

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

at least one temperature sensor... the at least one temperature sensor being passed through an associated recess in the panel heater and attached to the substrate

Methodology Applied
Scientific EffectTemperature sensing: Thermistor

Implementation Method 3

a substrate to be heated with a working side and a rear side facing away from the working side

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2649860B1Heating device for a household appliance and household appliance comprising such a heating device
Publication Date: 2017.08.16 BOSCH SIEMENS HAUSGERATE GMBH
  • EP2649860B1 patent drawingFigure 1

AI summary

The invention relates to a heating device (1) for a household appliance (H), said heating device comprising a heatable substrate (2) with a user side (3) and a rear side (4) facing away from the user side (3), at least one radiant heating element (5) arranged on the rear side (4) of the substrate (2), and at least one temperature sensor (6), the at least one temperature sensor (6) being guided through an intrinsic recess (7) in the radiant heating element (5) and fixed to the substrate (2). The household appliance (H) comprises at least one such heating device (1).