Electronic closed-loop control device for fireplaces comprising a lower combustion system

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Solution Overview

Problem

Existing wood-burning stove control systems lack automatic electronic evaluation and control programs that utilize temperature change and rate of temperature change to optimize combustion, leading to inefficient and pollutant-emitting operations due to manual adjustments and subjective operator intervention.

Innovation Solution

An electronic control device for a wood-burning stove with two combustion chambers, using temperature sensors to measure and evaluate temperature changes, and an electric motor to adjust flue outlets based on predefined parameters, allowing adaptive combustion control without operator intervention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If manual control of flue gas vent is used based on operator judgment, then device complexity is reduced, but combustion efficiency and emission control deteriorate due to subjective operator intervention and lack of temperature monitoring

Engineering Contradiction:
Improvecontrol system structureVSAvoidcombustion efficiency
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The control system automatically monitors flue gas temperature and adjusts the flue gas vent position without operator intervention. The microprocessor evaluates temperature changes over time and autonomously actuates the motor-driven vent to optimize combustion efficiency and reduce emissions.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The manual mechanical control of the flue gas vent is replaced with an automated motor-driven system controlled by a microprocessor that evaluates temperature sensor data. This substitution eliminates subjective operator judgment while maintaining relatively simple device structure.

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

2Extent of automation

If thermobimetal closing mechanism is used, then automation is improved, but reliability deteriorates because the system cannot respond to rapid temperature changes and increases pollutant emissions

Engineering Contradiction:
Improveautomatic air supply regulationVSAvoidresponse to temperature changes
Core Design Contradiction:
Extent of automationVSReliability

Solution Approach 1:

The system continuously monitors flue gas temperature through sensors and uses this feedback to dynamically adjust the flue gas vent position. The microprocessor evaluates temperature changes over time and rates of temperature change, enabling reliable response to varying combustion conditions without the lag inherent in thermobimetal mechanisms.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The control system dynamically adjusts the flue gas vent position based on real-time temperature evaluation. The motor-driven mechanism can respond rapidly to temperature changes, unlike static thermobimetal systems, ensuring optimal combustion control under varying conditions.

Inventive Principle:
Principle #15Dynamics

3Productivity

If temperature monitoring and automatic control program are implemented, then combustion efficiency is improved, but device complexity increases due to additional sensors and control electronics

Engineering Contradiction:
Improvecombustion efficiencyVSAvoidcontrol system structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The control system uses a single temperature sensor in the flue gas to autonomously evaluate combustion conditions and adjust the flue gas vent position. The microprocessor program independently determines optimal vent positioning based on temperature change patterns, achieving high combustion efficiency without requiring complex multi-sensor systems or external control inputs.

Inventive Principle:
Principle #25Self-service

4Object-generated harmful factors

If flue gas temperature monitoring is used to control vent position, then emission control is improved, but loss of information occurs without evaluation of temperature change over time and rate of temperature change

Engineering Contradiction:
Improvepollutant emissionsVSAvoidcombustion state assessment
Core Design Contradiction:
Object-generated harmful factorsVSLoss of information

Solution Approach 1:

The system continuously monitors flue gas temperature and evaluates both the absolute temperature value and the rate of temperature change over time. This feedback mechanism enables accurate assessment of combustion state and outgassing processes, allowing optimal adjustment of the flue gas vent to minimize pollutant emissions while avoiding premature fuel feed recommendations.

Inventive Principle:
Principle #23Feedback

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 precise, efficient, and low-emission combustion by automatically adjusting air supply and fuel addition, reducing pollutant emissions and meeting regulatory standards without requiring a mains connection.

Implementation Method 1

temperature sensors measure the temperature change over time and measure the rate of temperature change

Methodology Applied
Scientific EffectTemperature measurement:

Implementation Method 2

the control unit actuates an electric motor which, via transmission elements or a direct connection, actuates a flap closing the outlet

Methodology Applied
Scientific EffectElectric motor actuation: Linear Motor

Implementation Method 3

the combustion of the solid fuel in the upper combustion chamber

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP4204735B1Electronic closed-loop control device for fireplaces comprising a lower combustion system
Publication Date: 2025.11.26 MAXITROL GMBH & CO KG
  • EP4204735B1 patent drawingFigure 1
  • EP4204735B1 patent drawingFigure 2
  • EP4204735B1 patent drawingFigure 3

AI summary

The invention relates to a device that does not require operator intervention, operates without delay, does not require a mains connection, and meets the requirements of the regulations with respect to permissible pollutant emissions. The device consists of a control unit which is electrically connected to two temperature sensors and to a door contact switch and which actuates an actuator by means of an electric motor and transmission elements. The temperature is detected in the flue behind the outlet of the combustion chamber. The temperature sensors record the change in temperature over time and the speed of the change in temperature. The temperature target/actual evaluation is used to record the combustion state of the solid fuel. The degree of the outgassing process is determined by recording and evaluating the increase or decrease in temperature over time. The target/actual temperature over time compared to comparative values for optimising combustion is an adaptive system. Therefore, the composition of the solid fuel is taken into account for the optimum combustion process and the necessity of the new charging with solid fuel is determined by means of the programme and displayed by means of an optical signal transmitter. The device is used for electronic closed-loop control for a fireplace comprising a lower combustion system.