Catalytic Converter Oxygen Fill Level Regulation
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Solution Overview
Problem
Current engine control systems for three-way catalytic converters are slow to recognize deviations from the stoichiometric operating point, leading to delayed fuel adjustment and increased tailpipe emissions due to the late response in lambda regulation, as they rely on signals from jump lambda sensors that indicate breakthroughs only after oxygen storage capacity is exceeded.
Innovation Solution
A method that calculates a fill level profile using an inverted system model, allowing for real-time correction of the actual oxygen fill level in the catalytic converter, maintaining transitive relations between fill levels and adjusting the lambda setpoint value based on measured and modeled values to prevent breakthroughs, thereby ensuring the catalytic converter operates within the conversion window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lambda regulation relies on signals from jump lambda sensors downstream from the catalytic converter, then the system can detect breakthroughs of rich or lean exhaust gas, but the response is delayed until oxygen storage capacity is exceeded
Solution Approach 1:
The patent applies preliminary action by using a system model to calculate the actual oxygen fill level of the catalytic converter in advance, before breakthrough occurs. The control unit continuously updates the model with measured oxygen concentrations from upstream and downstream sensors, enabling early detection of fill level deviations. This allows the lambda regulation to be adjusted proactively before the jump lambda sensor detects breakthrough, thus reducing the response time while maintaining detection accuracy.
2Adaptability or versatility
If the oxygen fill level is allowed to vary freely, then the catalytic converter can handle load variations, but deviations from the conversion window increase tailpipe emissions
Solution Approach 1:
The patent implements feedback control by continuously measuring oxygen concentration both upstream and downstream of the catalytic converter, comparing the actual fill level against the fill level from the system model, and adjusting the lambda setpoint value accordingly. When the actual oxygen fill level deviates from the modeled value, the control unit modifies the lambda setpoint to correct the deviation, ensuring the catalytic converter remains within the conversion window and minimizing tailpipe emissions while maintaining adaptability.
Solution Approach 2:
The system model serves itself by using its own structure to calculate both the actual fill level and the expected fill level trajectory. The model is updated iteratively with measured values, allowing it to self-correct and maintain accurate predictions of oxygen storage behavior without external intervention, thereby enabling autonomous regulation within the conversion window.
Data Source
AI summary
A method for regulating filling an exhaust gas component (EGC) storage of a catalytic converter (CC) in the exhaust gas (EG) of an internal combustion engine. An actual fill level (AFL) of the EGC storage is ascertained using a first system model (FSM), to which signals of a first EG sensor projecting into the EG flow upstream from the CC and detecting a concentration of the EGC and a second EG sensor, downstream from the CC and exposed to the EG, are fed. A base lambda setpoint value for a first control loop (CL) is predefined by a second CL, which is adjusted to the AFL using the AFL ascertained using the FSM when the voltage of the second EG sensor indicates a breakthrough of rich/lean EG downstream from the CC and an excessively low/high AFL of the EGC storage. Also described is a control unit to perform the method.