Catalyst Fill Level Control for Lambda Deviation
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Solution Overview
Problem
Current engine control systems for three-way catalysts in internal combustion engines are slow to detect deviations from the optimal lambda (fuel/air) ratio, leading to increased tailpipe emissions due to delayed fuel adjustment, as they rely on signals from a switching-type lambda sensor behind the catalyst, which reacts late to departures from the conversion window.
Innovation Solution
Calculating and adjusting the fuel/air ratio based on the actual fill levels of multiple catalyst partial volumes, allowing for early detection and prevention of lambda deviations by prioritizing the oxygen fill level of the rear catalyst partial volume and optimizing the fill level reserve of the front partial volume to buffer dynamic disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If control is based on signals from a switching-type lambda sensor behind the catalyst, then lambda=1 can be displayed very precisely, but detection of departures from the conversion window is delayed
Solution Approach 1:
The patent calculates the actual fill level of the catalyst with a calculation model before a breakthrough occurs. By monitoring the fill level in advance and detecting trends toward saturation or exhaustion, the system can trigger preventive actions (adjusting fuel/air ratio) before the lambda sensor behind the catalyst shows a deviation, thus eliminating the time delay while maintaining measurement precision.
2Stability of the object's composition
If the catalyst oxygen storage capacity is used to balance out brief deviations from lambda=1, then conversion window stability is improved, but late detection of prolonged deviations leads to increased emissions
Solution Approach 1:
The patent implements a feedback mechanism where the calculated actual fill level is continuously monitored and compared against threshold values. When the fill level approaches saturation or exhaustion thresholds, the system provides feedback to adjust the fuel/air ratio in advance, preventing breakthrough and reducing emissions while maintaining the stabilizing effect of catalyst oxygen storage capacity.
3Reliability
If guidance control operates slowly to adjust for small deviations from lambda=1, then catalyst conversion efficiency is maintained, but response time to correct lambda deviations is insufficient
Solution Approach 1:
By calculating and monitoring the actual fill level in advance, the system can detect impending deviations before they occur. This preliminary detection enables faster corrective action to be taken, improving response speed while maintaining catalyst conversion efficiency through proactive rather than reactive control.
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 enables earlier detection of impending departures from the conversion window, reducing tailpipe emissions and allowing for timely correction, thus meeting stricter emission standards with lower catalyst costs and simpler control systems.
Implementation Method 1
By using a three-way catalyst, the stated pollutant components can be converted into nitrogen, carbon dioxide and water.
Implementation Method 2
Due to the oxygen storage capacity of the three-way catalyst, lambda=1 can still be present for several seconds behind the catalyst, a rich or lean lambda was subsequently adjusted in front of the catalyst.
Data Source
AI summary
The invention relates to a method for adjusting a fuel/air ratio of an internal combustion engine (10), comprising a catalyst volume (26) with a first catalyst partial volume (26.1) and a second catalyst partial volume (26.2). The second catalyst partial volume (26.2) is arranged downstream from the first catalyst partial volume (26.1). An actual filling level of an exhaust gas constituent in the catalyst volume (26) is calculated from operating parameters of the internal combustion engine (10) and the exhaust system (14) using a computing model, and is adjusted to a nominal value by modifying the fuel/air ratio. The adjustment is carried out first for the second catalyst partial volume (26.2) and only later for the first catalyst partial volume (26.1).