Induction Hob Boiling Point Detection via Optical Reflection

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Solution Overview

Problem

Existing cooking technologies face challenges in accurately predicting the boiling point of liquids, leading to inefficient energy use and prolonged cooking times, especially during simmering operations, due to unpredictable temperature curves and composition changes during heating.

Innovation Solution

A cooktop with a temperature sensor and control unit that directly measures the boiling temperature of the liquid during the heating-up phase, allowing for precise determination of the boiling point and setting a simmering temperature that is lower by a predetermined difference, thereby optimizing energy use and cooking speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the boiling point is predicted based on past temperature curves, then the control system can operate without direct measurement, but the prediction accuracy is low due to composition changes and atmospheric pressure variations

Engineering Contradiction:
Improveboiling point detection accuracyVSAvoidtemperature control system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex prediction algorithms and multiple sensors with a simple optical reflection principle. A light source and light receiver detect boiling by measuring changes in light reflection from the liquid surface, substituting mechanical/thermal measurement systems with an optical system that directly detects the boiling state without complex calculations

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

Solution Approach 2:

The liquid itself serves as the detection medium by reflecting light differently at its boiling point. The system uses the liquid's own physical property (light reflection characteristic change at boiling) to detect its own state, eliminating the need for external prediction models or additional measurement devices

Inventive Principle:
Principle #25Self-service

2Productivity

If the heating power is maintained at high levels to ensure cooking temperature, then cooking speed is fast, but energy consumption increases

Engineering Contradiction:
Improvecooking speedVSAvoidenergy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent implements a feedback control system where the light receiver continuously monitors the liquid's boiling state and sends signals to the control unit. Based on this real-time feedback, the control unit dynamically adjusts heating power - maintaining high power during rapid heating phase for fast cooking, then reducing to minimal power needed to maintain simmering temperature, thus optimizing both cooking speed and energy efficiency

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The heating power is made dynamic rather than static. The system transitions from high power during the heating-up phase to lower power during the holding phase, with continuous adjustment based on real-time boiling detection. This dynamic power management enables fast initial heating followed by energy-efficient temperature maintenance

Inventive Principle:
Principle #15Dynamics

3Manufacturing precision

If the temperature control is based on predicted boiling points, then the system can operate without real-time detection, but the simmering temperature accuracy is poor leading to prolonged cooking

Engineering Contradiction:
Improvesimmering temperature control precisionVSAvoidcooking time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The system uses real-time feedback from the light receiver that detects actual boiling occurrence. When boiling is detected, the control unit immediately adjusts the heating power to maintain the liquid at a temperature below the boiling point. This feedback-based control ensures precise simmering temperature maintenance, preventing both overheating and underheating, thus achieving accurate temperature control and optimal cooking time

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs preliminary heating at high power to quickly bring the liquid to boiling point, then immediately transitions to precision control mode. This preliminary action phase ensures rapid temperature rise followed by precise maintenance, combining fast heating with accurate temperature control to minimize total cooking time while achieving desired precision

Inventive Principle:
Principle #10Preliminary action

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 approach ensures precise control over the cooking temperature, reducing energy consumption and cooking time by eliminating errors in boiling point prediction, allowing for efficient simmering and faster cooking processes.

Implementation Method 1

a temperature sensor (12) for detecting a wall temperature of the cooking utensil element (14)

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 2

The hob (100) is an induction hob and the inductor (20) receives a high-frequency heating current

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2438796B1Hob comprising a temperature sensor
Publication Date: 2019.11.06 BOSCH SIEMENS HAUSGERATE GMBH
  • EP2438796B1 patent drawingFigure 1~2
  • EP2438796B1 patent drawingFigure 3

AI summary

The invention relates to a hob comprising at least one heating zone (10), a temperature sensor (12) for detecting the temperature of a cookware element (14) placed on the heating zone (10), and a control unit (16) for operating the heating zone, wherein the control unit (16) is designed to heat up the cookware element (14) in a heat-up phase (26) and to control the temperature of the cookware element (14) to a target temperature (TS) in a holding phase (32) in at least one operating mode. In order to enable an energy-saving simmer operation, it is proposed that the control unit (16) be designed to detect a boiling point (TB) of the liquid contained in the cookware element (14) during the heat-up phase (26) and to determine the target temperature (TS) according to the boiling point (TB).