Heating System Fuel-Air Ratio Calibration via Ionization Signal

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Solution Overview

Problem

Existing methods for calibrating fuel-air ratio sensors in gas burners emit more pollutants and require the burner to be offline for an extended period, disrupting normal operation.

Innovation Solution

A method that involves generating a temporary, pulse-like change in fluid supply parameters to monitor combustion parameters, allowing for real-time adjustment of the fuel-air ratio without shutting down the system, thereby reducing emissions and enabling calibration during normal operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the gas burner is run over its entire power range for calibration, then the sensors can be calibrated accurately, but more pollutants are emitted during calibration

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

Solution Approach 1:

The patent applies partial action by performing sensor calibration at selected power points rather than running the entire power range. The control unit identifies calibration points within the operating range and performs calibration only at these specific points, reducing overall emissions while maintaining sufficient calibration accuracy for sensor functionality.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent changes the calibration approach from fixed full-range calibration to dynamic calibration based on actual operating parameters. The control unit monitors operating conditions and adjusts calibration timing and extent based on current power settings, allowing calibration to be performed with minimal deviation from optimal operating conditions, thereby reducing pollutant emissions.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If the gas burner is run over its entire power range for calibration, then the sensors can be calibrated accurately, but the gas burner is not available for normal operation during calibration

Engineering Contradiction:
Improvesensor calibration accuracyVSAvoidburner availability
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent performs calibration only at selected power points rather than the entire power range, significantly reducing the time the burner is unavailable. By calibrating at fewer, strategically chosen points, the system maintains sensor accuracy while minimizing disruption to normal heating operations and improving overall burner availability.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The control unit identifies and prepares calibration points in advance based on expected operating conditions. By pre-determining when and where calibration should occur within the operating range, the system can perform calibration during naturally occurring transition periods or low-demand times, minimizing impact on productivity and ensuring burner availability during critical heating periods.

Inventive Principle:
Principle #10Preliminary action

3Object-generated harmful factors

If a temporary fluid supply change is generated as a function of last signal maximum, then the fuel-air ratio can be controlled accurately with minimal emissions, but the control logic becomes more complex

Engineering Contradiction:
Improvepollutant emissionsVSAvoidcontrol logic complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The control unit uses feedback from the ionization current signal (last signal maximum) to dynamically adjust the fluid supply change during calibration. By monitoring the combustion parameter response and comparing it against expected values, the system automatically adjusts fuel and air supply to maintain optimal combustion, minimizing pollutant emissions through closed-loop control that adapts to actual operating conditions.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The calibration process is designed to be self-regulating, where the control unit automatically determines the appropriate fluid supply adjustments based on the measured signal maximum and combustion response. The system performs self-diagnosis and self-adjustment without requiring external intervention or complex manual procedures, simplifying operation while maintaining emission control through automated feedback mechanisms.

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

This approach ensures accurate fuel-air ratio control with minimal emissions and no downtime, enhancing the reliability and longevity of the heating system by preventing incorrect settings and reducing wear and tear.

Implementation Method 1

at least one combustion parameter, in particular an ionization current, is determined by measurement on a flame of the heating system

Methodology Applied
Scientific EffectIonization: Ionisation

Data Source

PatentEP3290801B1Method for controlling a fuel/air ratio in a heating system and a control unit and a heating system
Publication Date: 2020.08.12 ROBERT BOSCH GMBH
  • EP3290801B1 patent drawingFigure 1
  • EP3290801B1 patent drawingFigure 2
  • EP3290801B1 patent drawingFigure 3~4

AI summary

The invention relates to a method for controlling a fuel-air ratio in a heating system, comprising the following steps: • Generating a temporary, temporal change in the fluid supply (60) of a fluid supply parameter (62) as a function of a previous signal maximum (64), • Determining a new signal maximum (96) of a temporal change in at least one combustion parameter (98) correlated with the temporal change in the fluid supply (60), • Increasing an error variable if the new signal maximum (96) falls below a lower signal limit (82), • Executing an error response, in particular calibrating and/or shutting down the heating system, as a function of the error variable. 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.