Exhaust Gas Catalytic Converter Fill Level Detection
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Solution Overview
Problem
Existing control methods for three-way catalytic converters in vehicles detect deviations from the optimal operating point (lambda=1) late, leading to inefficient conversion of harmful exhaust gases, and require complex models and accurate sensor signals to manage fill levels accurately.
Innovation Solution
A method using upstream sensors to detect operating parameters like lambda values and integrating them with simple integrator models to ascertain fill levels of both catalytic converters, eliminating the need for downstream sensor signals and reducing computational time, while considering temperature and storage capacity for precise calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If downstream lambda sensors are used to detect deviations from catalytic converter window, then control accuracy is improved, but detection timing is delayed and computing time increases
Solution Approach 1:
The patent applies preliminary action by calculating the fill level of the first catalytic converter upstream from the second catalytic converter using the integrator model, before the exhaust gas actually reaches the second converter. This allows the control system to anticipate and respond to deviations from the catalytic converter window earlier, rather than waiting for downstream sensors to detect the deviation after it has already occurred.
2Measurement precision
If complex models are used to ascertain fill levels accurately, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by using an integrator model that processes the lambda sensor signal through mathematical integration to derive fill level information. This approach transforms the complex dynamic behavior of the catalytic converter into a simpler mathematical operation, achieving accurate fill level detection without requiring complex physical models of the converter's internal state.
3Measurement precision
If downstream sensor signals are used to determine second catalytic converter fill level, then measurement precision is improved, but computing time increases due to time offset
Solution Approach 1:
The patent eliminates the time offset problem by calculating the fill level of the first catalytic converter upstream from the second converter before the exhaust gas reaches the second converter. This preliminary calculation allows the system to determine the state of the first converter without waiting for downstream sensor signals, thereby reducing computing time while maintaining detection accuracy.
Solution Approach 2:
The patent uses the integrator model as an intermediary that processes the lambda sensor signal to provide fill level information for both catalytic converters. This intermediary approach allows the system to infer the state of the second converter based on the processed signal from the first converter, eliminating the need for direct downstream sensor measurements and reducing computational delays.
Data Source
AI summary
A method for ascertaining fill levels of first and second exhaust gas catalytic converters in an exhaust gas system downstream from an internal combustion engine with respect to at least one exhaust gas component. The method includes detecting, using a sensor upstream from the first exhaust gas catalytic converter, at least one operating parameter of the exhaust gas system, ascertaining the fill level of the first exhaust gas catalytic converter based on the detected at least one operating parameter using a first calculation rule, ascertaining a total fill level of the first exhaust gas catalytic converter and second exhaust gas catalytic converter based on the ascertained at least one operating parameter using a second calculation rule, and ascertaining the fill level of the second exhaust gas catalytic converter as a difference between the total fill level and the fill level of the first exhaust gas catalytic converter.