Heating System Fuel-Air Ratio Calibration via Temporary Fluid Supply Changes

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Solution Overview

Problem

Existing methods for calibrating fuel-air ratio sensors in gas burners result in increased pollutant emissions and downtime, as they require running the burner over its entire power range, which is not available for normal operation during calibration.

Innovation Solution

A method that generates temporary fluid supply changes to determine relative signal maxima of combustion parameters, allowing for precise calibration of the fuel-air ratio without additional emissions, by selecting fluid supply changes based on burner performance parameters, enabling calibration during normal operation with minimal disruption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the gas burner is operated across its entire power range for calibration, then the sensor calibration is improved, but pollutant emissions increase and the gas burner becomes unavailable for normal operation

Engineering Contradiction:
Improvesensor calibrationVSAvoidpollutant emissions
Core Design Contradiction:
Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The calibration process is segmented into multiple individual measurement points across the power range, with temporary small fluid supply changes at each point, rather than continuous operation across the entire range. This allows calibration to be performed at discrete intervals with minimal emissions at each segment.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The fluid supply parameter is changed periodically in small temporary increments during normal operation, allowing the system to perform multiple small calibration measurements instead of one large continuous calibration. This periodic action maintains calibration accuracy while minimizing total emissions.

Inventive Principle:
Principle #19Periodic action

2Measurement precision

If the gas burner is operated across its entire power range for calibration, then the sensor calibration is improved, but the gas burner is unavailable for normal operation during calibration

Engineering Contradiction:
Improvesensor calibrationVSAvoidavailability for normal operation
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The system performs calibration measurements during normal operation by introducing temporary fluid supply changes, rather than requiring a separate dedicated calibration period. This preliminary integration of calibration into normal operation ensures the burner remains available while still achieving calibration.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The calibration process is integrated into continuous normal operation, allowing both calibration and heating functions to occur simultaneously. The temporary fluid supply changes are superimposed on ongoing operation, maintaining continuous useful action without interruption.

Inventive Principle:
Principle #20Continuity of useful action

3Object-generated harmful factors

If small fluid supply changes are made during normal operation, then pollutant emissions are minimized and the system remains available, but the detection of fault conditions becomes more challenging

Engineering Contradiction:
Improvepollutant emissionsVSAvoidfault condition detection
Core Design Contradiction:
Object-generated harmful factorsVSDifficulty of detecting and measuring

Solution Approach 1:

The system uses feedback from combustion parameters (such as flame ionization current) to detect changes resulting from temporary fluid supply variations. By monitoring the response of combustion parameters to small fluid changes, the system can detect fault conditions even with minimal emissions, as the feedback signal amplifies the measurement effect.

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

This approach minimizes pollutant emissions, allows for precise and reliable detection of faulty states, and reduces wear and tear on the heating system by avoiding unnecessary calibration processes, thereby increasing system durability and safety.

Implementation Method 1

determine a relative signal maximum of a temporal change of at least one combustion parameter correlated with the temporal change in fluid supply

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP3290796B1Method for controlling a fuel/air ratio in a heating system and a control unit and a heating system
Publication Date: 2021.01.27 ROBERT BOSCH GMBH
  • EP3290796B1 patent drawingFigure 1
  • EP3290796B1 patent drawingFigure 2~3
  • EP3290796B1 patent drawingFigure 4

AI summary

The invention relates to a method for controlling a fuel-air ratio in a heating system. It is proposed that the method comprises the following steps: • Generating a temporary, temporal fluid supply change (60) of a fluid supply parameter (62), • Attempting to determine a relative signal maximum (80) of a temporal change of at least one combustion parameter correlated with the temporal fluid supply change (60), • Determining a fault condition if the relative signal maximum (80) falls below a signal lower limit (98), if a relative signal maximum (80) has been determined, • Calibrating the heating system if a fault condition is detected and that the fluid supply change (60) is selected depending on a burner power parameter. The invention also relates to a control unit configured for carrying out the method according to the invention and to a heating system with the control unit according to the invention.