Catalyst Fill Regulation Using Multistaged Exhaust Probe Adaptation
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Solution Overview
Problem
Current engine control systems for three-way catalysts in internal combustion engines are slow to respond to deviations from the stoichiometric operating point, leading to late identification of leaving the conversion window, resulting in heavier tailpipe emissions due to the delayed feedback from lambda step probes.
Innovation Solution
A multistaged adaptation method that processes signals from different regions of the exhaust gas probe downstream of the catalyst, combining continuous and discontinuous corrections to accurately manage the oxygen fill level, allowing for timely recognition and prevention of leaving the conversion window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a lambda step probe after the three-way catalyst is used for servo control, then lambda=1 can be indicated very accurately, but the response to leaving the conversion window is delayed resulting in heavier tailpipe emissions
Solution Approach 1:
The patent applies preliminary action by using a model-based feedforward control that predicts and prevents conversion window departure before it occurs. The system calculates a target lambda value that proactively adjusts the air-fuel ratio to keep the catalyst within the conversion window, rather than reacting after the lambda step probe detects a violation. This anticipatory control eliminates the delayed response inherent in traditional feedback-only systems.
Solution Approach 2:
The patent combines feedback from the lambda step probe with model-based predictions to improve response time. While the lambda step probe continues to provide accurate lambda=1 indication, its signal is now used to validate and correct the model-based feedforward control, creating a hybrid system that benefits from both the predictive capability of the model and the precision of the probe.
2Loss of time
If a model-based regulation of catalyst fill level is used, then timely recognition of conversion window departure is enabled, but uncertainties of measured or model variables reduce regulation robustness
Solution Approach 1:
The patent uses feedback from the lambda step probe to correct uncertainties in the model-based regulation. The probe's accurate lambda=1 indication serves as a reference signal that validates the model's predictions and corrects deviations caused by uncertainties in measured variables or model parameters, thereby maintaining regulation robustness while enabling timely recognition of conversion window departure.
Solution Approach 2:
The patent dynamically adjusts the target lambda value based on the calculated oxygen fill level of the catalyst. By changing the lambda setpoint according to the catalyst's oxygen storage state, the system optimizes the air-fuel ratio to maintain operation within the conversion window while compensating for model uncertainties through continuous adaptation.
Data Source
AI summary
A method is proposed for regulating a fill level of an exhaust component storage of a catalyst (26) of an internal combustion engine (10), wherein the regulating of the fill level is done by using a system model (100), comprising a catalyst model (102), and wherein uncertainties of measured or model variables influencing the regulating of the fill level are corrected by an adaptation, which is based on signals of an exhaust gas probe (34) arranged at the outlet side of the catalyst (26). The method is characterized in that the adaptation takes multiple pathways (200, 210, 220), wherein signals from different signal regions (260, 280, 300) of the exhaust gas probe (34) situated at the outlet side are processed on different pathways. An independent claim is addressed to a controller designed to carry out the method.