Induction Cooktop Thin Film Temperature Control

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Solution Overview

Problem

Conventional induction heated cooktops face inefficiencies in heating non-magnetic objects and have limitations in temperature control, leading to potential damage due to rapid temperature increases and inaccurate temperature measurement, especially when using thin films for heat transfer.

Innovation Solution

An induction heated cooktop design featuring an upper plate with a working coil, a thin film on the plate or its bottom, and dual temperature sensors to measure the thin film and upper plate temperatures, controlled by a microcontroller unit to manage the coil's output based on threshold temperatures, preventing overheating and ensuring accurate temperature management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a conventional induction heating method is used to heat non-magnetic objects, then heating efficiency is low and cooking time is long, but adding a heating plate increases device complexity and energy loss

Engineering Contradiction:
Improveheating efficiencyVSAvoiddevice complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The cooktop is designed to universally heat both magnetic and non-magnetic objects using a single induction heating mechanism. The system detects the type of object and automatically adjusts heating parameters, eliminating the need for separate heating mechanisms for different material types.

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

Solution Approach 2:

A thin film layer is introduced as an intermediary between the induction coil and the target object. This thin film can be inductively heated and transfers heat to both magnetic and non-magnetic objects, serving as a universal heating interface that improves heating efficiency without requiring multiple specialized components.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Speed

If direct induction heating is used, then heating speed is fast, but temperature control precision deteriorates and objects may be damaged due to excessive heat

Engineering Contradiction:
Improveheating speedVSAvoidtemperature control precision
Core Design Contradiction:
SpeedVSMeasurement precision

Solution Approach 1:

The system incorporates temperature sensors that continuously monitor the temperature of the thin film and the target object. A microcontroller receives this temperature data and dynamically adjusts the induction coil output to maintain optimal heating, preventing overheating and damage while preserving fast heating speeds.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The induction heating system dynamically adjusts its operating parameters in real-time based on temperature feedback. The microcontroller modulates the coil output continuously to maintain the thin film and object temperatures within safe operating ranges, enabling precise temperature control without sacrificing heating speed.

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If a thin film is used for indirect heating, then heating versatility improves, but the thin film may be damaged by rapid temperature increases

Engineering Contradiction:
Improveheating versatilityVSAvoidthin film reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

Temperature sensors are positioned to monitor the thin film temperature directly, and the microcontroller uses this feedback to control the induction coil output. This prevents the thin film from experiencing rapid temperature increases beyond its tolerance, ensuring its reliability while maintaining heating versatility.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system pre-establishes safe temperature thresholds for the thin film through calibration. The microcontroller actively prevents temperature excursions beyond these thresholds by adjusting coil output in advance, cushioning the thin film against thermal damage while preserving its ability to heat various object types.

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

4Ease of manufacture

If conventional temperature sensors are used, then device cost is low, but measurement accuracy deteriorates at high temperatures above 100°C

Engineering Contradiction:
Improvedevice costVSAvoidtemperature measurement accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The system changes the operating parameters of the temperature sensing mechanism to function accurately at high temperatures. By adjusting sensor characteristics and compensation parameters, the system achieves accurate temperature measurement above 100°C while maintaining cost-effectiveness through efficient sensor utilization.

Inventive Principle:
Principle #35Parameter changes

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 enables efficient heating of both magnetic and non-magnetic objects, prevents damage from rapid temperature increases, and provides precise temperature control, enhancing safety and cooking efficiency.

Implementation Method 1

In the induction heating method, a target heating object may be heated by eddy current generated in the target heating object made of a metal material, using an electrical field generated around a coil when a high frequency power having a predetermined magnitude is applied to the coil.

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

In the electrical resistive heating method, a target heating object may be heated based on current flowing through a metal resistance wire or a non-metallic heating element, such as Silicon Carbide (SIC), to generate heat which is then transferred to the target heating object

Methodology Applied
Scientific EffectResistive heating: Joule Heating

Implementation Method 3

a thin film (1020) disposed on at least one of a top of the upper plate (15, 1010, 1115) or a bottom of the upper plate (15, 1010, 1115)

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

A resistance value of the thermistor included in the conventional cooktop may change based on a temperature, enabling the thermistor to measure a temperature based on the changed in the resistance value.

Methodology Applied
Scientific EffectThermistor effect: Thermistor

Data Source

PatentEP4181627A1Induction heating type cooktop with increased heating stability
Publication Date: 2023.05.17 LG ELECTRONICS INC
  • EP4181627A1 patent drawingFigure 1
  • EP4181627A1 patent drawingFigure 2
  • EP4181627A1 patent drawingFigure 3

AI summary

An induction heating type cooktop includes: an upper plate coupled to a top of a case, the upper plate being configured to support a target object, a working coil provided in the case and configured to heat the target object, a thin film disposed on at least one of a top of the upper plate or a bottom of the upper plate, a first temperature sensor configured to measure a temperature of the thin film, a second temperature sensor configured to measure a temperature of the upper plate, and a controller. The controller is configured to control the working coil to heat the target object based on a target output, and control an output of the working coil based on the measured temperature of the thin film and the measured temperature of the upper plate.