Exhaust Gas Catalytic Converter Diagnosis via Sensor Ratio
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Solution Overview
Problem
Existing methods for diagnosing exhaust gas catalytic converters in internal combustion engines lack reliability and accuracy, particularly in detecting local damage and ensuring compliance with stringent emission regulations without additional components or active intervention in the air-to-fuel ratio.
Innovation Solution
A method and device that utilize upstream and downstream exhaust gas sensors to estimate conversion rates of exhaust gas components, integrate sensor signals over time or distance, and compare them with predetermined rates to diagnose converter functionality, detect errors, and identify local damage by analyzing temperature curves and driving profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing diagnostic methods are used, then the diagnostic process is simple, but the reliability and accuracy of detecting local damage is insufficient
Solution Approach 1:
The patent segments the exhaust gas tract into multiple measurement zones by positioning sensors at different locations (upstream and downstream of the catalytic converter). This segmentation allows independent evaluation of different regions, enabling detection of local damage that would be missed by single-point measurements, thereby improving diagnostic reliability without requiring complex additional equipment.
Solution Approach 2:
The patent introduces exhaust gas sensors as intermediary devices that indirectly measure catalytic converter performance by detecting exhaust gas composition changes. These sensors act as mediators between the catalytic converter and the diagnostic system, providing reliable data about conversion efficiency and local damage without requiring direct inspection or complex internal measurements.
2Measurement precision
If additional components are added to improve diagnosis accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent makes existing exhaust gas sensors serve multiple functions: they simultaneously monitor exhaust gas composition for emission control and provide diagnostic data for catalytic converter health assessment. This multi-functionality improves measurement precision for diagnostics without adding dedicated diagnostic components, thereby avoiding increased system complexity.
Solution Approach 2:
The diagnostic system utilizes data already being collected by the exhaust gas sensors for their primary emission monitoring function. By self-service reusing this existing data for diagnostic purposes, the system achieves improved measurement precision without requiring additional sensors or components, thus maintaining simplicity.
3Measurement precision
If active intervention in air-to-fuel ratio is used, then diagnostic accuracy improves, but ease of operation deteriorates
Solution Approach 1:
The patent employs feedback by continuously monitoring exhaust gas composition with sensors positioned upstream and downstream of the catalytic converter. This feedback mechanism provides real-time data on conversion efficiency without requiring active intervention in the air-to-fuel ratio, maintaining operational simplicity while achieving accurate measurement of converter performance through passive observation of exhaust gas changes.
4Measurement precision
If integration over time or distance is performed, then diagnostic accuracy improves, but loss of time increases
Solution Approach 1:
The patent performs integration of sensor signals over predetermined periods or distances, applying partial action by selecting specific integration windows that balance accuracy requirements with time constraints. This approach achieves sufficient measurement precision for diagnostic purposes without unnecessarily extending the diagnosis time, optimizing the trade-off between accuracy and speed.
Data Source
AI summary
A first exhaust gas sensor signal (vls_up) of a first exhaust gas sensor (AS1) is detected. In addition, a second exhaust gas sensor signal (vls_down) of a second exhaust gas sensor (AS2) is detected. A relevant first estimated value of an emission of at least one exhaust gas component is determined in relation to a position of the first exhaust gas sensor (AS1) in the exhaust gas tract as a function of the first exhaust gas sensor signal (vls_up) and a relevant second estimated value of an emission of the at least one exhaust gas component is determined in relation to a position of the second exhaust gas sensor (AS2) in the exhaust gas tract as a function of the second exhaust gas sensor signal (vls_down). A conversion rate (K) of the at least one exhaust gas component is estimated as a function of a ratio of the second estimated value and the first estimated value of the determined emission. The exhaust gas catalytic converter is diagnosed as a function of the determined conversion rate (K).