Model-Based Catalyst Fill Level Regulation for Lambda Offset Correction
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Solution Overview
Problem
Existing internal-combustion engine control systems often fail to accurately detect and correct offsets in lambda values between the catalyst and upstream/downstream sensors, leading to late detection of catalyst window exits and inefficient pollutant emission control.
Innovation Solution
A model-based regulation method that uses theoretical catalyst models to detect and correct deviations in lambda values by adjusting the air-fuel mixture, incorporating signals from both upstream and downstream sensors to adapt the catalyst fill level and compensate for sensor inaccuracies, ensuring early detection and prevention of catalyst window exits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a jump lambda sensor behind the catalyst is used to detect catalyst window exits, then lambda=1 can be displayed very accurately, but the detection of exit from the catalyst window is delayed
Solution Approach 1:
The patent applies preliminary action by using a model-based regulation that predicts and detects impending breakthroughs before they actually occur. The system monitors the average oxygen fill level of the catalyst using a path model, enabling early warning and correction before the catalyst window exit is complete, thus reducing detection delay while maintaining measurement accuracy
2Loss of time
If a model-based regulation of the catalyst fill level is used, then impending breakthroughs can be detected early, but the offset between lambda in front of and behind the catalyst is not correctly indicated
Solution Approach 1:
The patent applies feedback by continuously comparing the modeled fill level with the actual lambda measurement behind the catalyst and using this information to correct the model parameters. The system uses the lambda sensor signal to provide feedback that adjusts the path model parameters, ensuring both early detection capability and accurate offset indication are maintained simultaneously
3Productivity
If the average oxygen fill level of the catalyst is modeled using a path model, then the fill level can be monitored continuously, but the fill level is not directly measurable and must be modeled
Solution Approach 1:
The patent applies the intermediary principle by introducing a path model as a mediator between the unmeasurable fill level and the measurable lambda signals. The model acts as an intermediary that translates the relationship between fuel injection, exhaust gas composition, and catalyst fill level into a continuous monitoring capability, while the lambda sensor provides verification to maintain reliability
Data Source
AI summary
A method for operating an internal-combustion engine having an exhaust gas catalyst, a first exhaust gas sensor upstream of the exhaust gas catalyst and a second exhaust gas sensor downstream of the exhaust gas catalyst. A fill level of an exhaust gas component that can be stored in the exhaust gas catalyst is determined using a theoretical catalyst model, into which, as the input value, a signal of the first exhaust gas sensor (a first signal); a signal of the second exhaust gas sensor (a second signal); and a target signal are provided. The target signal corresponds to the signal that would be expected at the determined fill level in the exhaust gas catalyst. The catalyst model is reinitiated when the deviation of the second signal from the target signal exceeds a predetermined threshold value. The fill level is also regulated, and an air-fuel mixture is adjusted.