Combustion Air Path Sensing for Gas Heater Mixture Control

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Solution Overview

Problem

Gas-fired heating appliances with electronically controlled gas-air mixtures face deviations due to disturbance variables, leading to reduced performance and increased risk of thermoacoustic disturbances, with existing technologies failing to account for the specific influence of humidity and exhaust gas recirculation on mixture formation.

Innovation Solution

Measuring properties such as humidity and temperature in the combustion air path, using sensors and evaluation electronics to detect and correct deviations, allowing for precise control and adjustment of exhaust gas recirculation, and identifying leaks or installation errors through cross-correlation with empirical data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If tolerance bands for gas-air mixture are widened to account for unknown disturbance variables, then the heating appliance can operate more robustly under uncertain conditions, but the manufacturing precision and emission control deteriorate

Engineering Contradiction:
Improverobust operationVSAvoidmixture ratio precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent implements feedback control by continuously measuring disturbance variables (humidity, temperature, exhaust gas recirculation) and using these measurements to dynamically adjust the gas-air mixture ratio. This closed-loop approach allows the system to maintain precision despite varying operating conditions, resolving the contradiction between robustness and precision.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically changes operating parameters (gas-air ratio, exhaust gas recirculation rate) based on measured disturbance variables. By adapting parameters in real-time according to actual conditions rather than using fixed tolerance bands, the system achieves both robust operation and precise emission control.

Inventive Principle:
Principle #35Parameter changes

2Object-generated harmful factors

If the operating range is narrowed to ensure compliance with emission limits under all disturbance conditions, then emission control improves, but the productivity and usability of the heating appliance deteriorate

Engineering Contradiction:
Improveemission controlVSAvoidheating performance
Core Design Contradiction:
Object-generated harmful factorsVSProductivity

Solution Approach 1:

Continuous measurement and feedback control enable the system to maintain precise emission control while operating across a wider range of conditions. The system adapts to disturbances in real-time, eliminating the need for conservative operating range limitations.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs preliminary measurements of disturbance variables (humidity, temperature, exhaust gas recirculation) before combustion adjustments are made. This allows proactive compensation for disturbances, maintaining emission compliance without restricting the operating range.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If complex ignition algorithms with multiple attempts are implemented to handle mixture deviations, then the reliability of ignition improves, but the loss of time and operational complexity increases

Engineering Contradiction:
Improveignition reliabilityVSAvoidignition time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary measurement and correction of the gas-air mixture ratio before the ignition attempt. By pre-adjusting the mixture based on measured disturbance variables, the system achieves reliable ignition on the first attempt, eliminating the need for multiple retry algorithms and reducing ignition time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses real-time measurements of disturbance variables to automatically self-adjust the mixture ratio before ignition. This self-correction mechanism ensures optimal ignition conditions without requiring complex external control algorithms or multiple attempts.

Inventive Principle:
Principle #25Self-service

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

Enhances operational safety and efficiency by reducing tolerance limits and enabling robust operation, with improved detection of leaks and precise control of gas-air mixtures, thereby minimizing emissions and thermoacoustic disturbances.

Implementation Method 1

at least one property of the air in a combustion air path of a gas-fired heating appliance is measured using at least one sensor

Methodology Applied
Scientific EffectHumidity measurement: Hygrometer

Implementation Method 2

at least one property of the air in a combustion air path of a gas-fired heating appliance is measured using at least one sensor

Methodology Applied
Scientific EffectTemperature measurement: Thermocouple

Implementation Method 3

Exhaust gas recirculation affects the properties of the air in the combustion air path

Methodology Applied
Scientific EffectGas mixing: Diffusion

Implementation Method 4

determine the size and location of a leak between an exhaust gas path and a combustion air path

Methodology Applied
Scientific EffectGas detection: Absorption Spectroscopy

Data Source

PatentEP4043792B1Method and arrangement for the use of combustion products or properties of the air in the combustion air path of a gas-fired heater for its control and / or state analysis
Publication Date: 2026.03.11 VAILLANT GMBH(DE)
  • EP4043792B1 patent drawingFigure 1
  • EP4043792B1 patent drawingFigure 2
  • EP4043792B1 patent drawingFigure 3~4

AI summary

The invention relates to a method and an arrangement for using at least one property of the air in a combustion air path (21, 22) of a gas-fired heating appliance (1) for measuring exhaust gas recirculation and for its control and/or condition analysis, wherein the property is measured by means of at least one sensor (17, 19) and its behavior is compared with empirical values ​​or calibration data in relation to known processes in the heating appliance (1), so that changes in the property can be detected and used for controlling the heating appliance (1) and/or for status messages. The invention enables increased operational safety and a reduction in tolerance limits in the control of a heating appliance (1), so that it can be operated more efficiently and robustly, at least under certain conditions.