Catalytic Converter Fill Level Regulation in Coasting Mode
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Solution Overview
Problem
Existing engine control systems struggle to accurately and promptly regulate the fill level of a three-way catalytic converter, leading to delayed recognition of departures from the conversion window, resulting in elevated tailpipe emissions and inefficiencies in pollutant conversion.
Innovation Solution
A method that predicts changes in the actual fill level during coasting phases using sensors and control variables, employing an inverted system model to adjust the air/fuel mixture proactively, and utilizing signals from an exhaust gas probe before the catalytic converter to recognize impending departures from the conversion window, thereby enabling timely corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional lambda regulation systems are used with probes before and after the catalytic converter, then the system can maintain the conversion window under normal operating conditions, but the system responds too slowly to detect departures from the conversion window during coasting modes, resulting in elevated emissions
Solution Approach 1:
The patent applies preliminary action by predicting the fill level trajectory during coasting modes before actual departures from the conversion window occur. The prediction model uses pre-stored lambda-time characteristic values and current operating parameters to forecast future fill levels, enabling the control system to take preventive action rather than reacting to delays in probe detection.
Solution Approach 2:
The patent inverts the conventional approach by using an inverted system model that predicts fill level changes during coasting modes rather than relying on delayed feedback from probes. This inversion allows the system to anticipate departures from the conversion window by modeling the reverse relationship between lambda adjustments and fill level changes, providing earlier warning of impending issues.
2Ease of operation
If the catalytic converter oxygen fill level is allowed to vary naturally during coasting modes, then the system operates with fewer control interventions, but the fill level may depart from the conversion window leading to increased pollutant emissions
Solution Approach 1:
The system performs preliminary action by predicting fill level trajectories during coasting modes and calculating required lambda adjustments in advance. This allows the control system to maintain simplicity during normal operation while being prepared to intervene promptly when predictions indicate upcoming departures from the conversion window, thus preventing emissions without requiring constant active control.
3Reliability
If the system uses a prediction model with stored lambda-time characteristic values, then it can anticipate fill level changes during coasting modes, but the system complexity and computational requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-storing lambda-time characteristic values during engine operation. These characteristic values are captured in advance and stored in memory for later use during coasting modes, eliminating the need for complex real-time calculations while maintaining high prediction accuracy. The system prepares prediction data beforehand, reducing computational burden during actual coasting events.
4Object-generated harmful factors
If the system intervenes frequently to maintain fill level during coasting modes, then emissions are reduced, but fuel consumption increases due to unnecessary fuel metering adjustments
Solution Approach 1:
The system uses preliminary action by predicting fill level trajectories only during coasting modes when fuel metering is already reduced or shut off. The prediction model determines whether intervention is actually needed based on forecasted departures from the conversion window, allowing the system to maintain simplicity and avoid unnecessary fuel adjustments while still preventing emissions when truly required.
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 improves the regulation of the catalytic converter fill level, reducing emissions and ensuring a more balanced fill level reserve, which helps maintain the conversion window even during dynamic disruptions, thus meeting stricter regulatory requirements.
Implementation Method 1
a first exhaust gas probe, which projects into the exhaust gas flow upstream from the catalytic converter and detects a concentration of the exhaust gas constituent
Implementation Method 2
The aforesaid pollutant components can be converted by using a three-way catalytic converter
Implementation Method 3
a plurality of combustion products, of which hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) are subject to regulatory limits
Implementation Method 4
a plurality of combustion products, of which hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) are subject to regulatory limits
Implementation Method 5
Because of the oxygen storage capability of the three-way catalytic converter, a lambda=1 condition can still exist downstream from the three-way catalytic converter for several seconds even after a rich or lean lambda has been established before the three-way catalytic converter
Data Source
AI summary
A method for regulating a filling of an exhaust gas component reservoir of a catalytic converter in the exhaust of an internal combustion engine. An actual fill level of the exhaust gas component reservoir is ascertained using a first system model, and in which a baseline lambda setpoint for a first control loop is predefined by a second control loop in which an initial value for the baseline lambda setpoint is converted, by a second system model identical to the first system model, into a fictitious fill level; the fictitious fill level is compared with a setpoint for the fill level; and the baseline lambda setpoint is iteratively modified as a function of the comparison result. At the beginning of a coasting phase, the baseline lambda setpoint is calculated based on signals of sensors and control variables which relate to the delivery of air and/or fuel to combustion chambers.