Air Flow Sensor Drift Diagnosis Without EGR Cutoff
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Solution Overview
Problem
Current diagnostic methods for air flow meters in heat engines, particularly those detecting drift or intake leaks, require cutting off exhaust gas recirculation, which reduces efficiency and increases emissions, and lack precision due to reliance on incomplete or unreliable data sources like turbocharger speed sensors or pressure sensors not present on all engines.
Innovation Solution
A diagnostic method that measures fresh air flow directly using a flow meter, estimates air flow through a filling model, and calculates additional flow rates using hydrodynamic equations, allowing for continuous diagnosis without shutting off exhaust gas recirculation by calculating a median of these values and comparing them to the flow meter reading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If exhaust gas recirculation is cut off for diagnostic purposes, then air flow meter diagnosis can be performed, but emission control efficiency deteriorates and fuel consumption increases
Solution Approach 1:
The patent applies partial action by using only the necessary portion of recirculation cutoff (brief moments when diagnostic confidence is low) rather than complete or prolonged cutoff. The diagnostic system continuously monitors multiple air flow values and maintains recirculation whenever possible, cutting off only briefly when the median value falls outside the confidence interval, thus minimizing energy loss while ensuring diagnostic reliability.
Solution Approach 2:
The patent implements continuity of useful action by maintaining exhaust gas recirculation continuously whenever diagnostic confidence is high. The system only interrupts recirculation temporarily when diagnostic uncertainty arises, allowing the beneficial recirculation process to continue uninterrupted for the majority of the diagnostic period, thereby reducing overall fuel consumption and emissions.
2Reliability
If exhaust gas recirculation is cut off for diagnostic purposes, then air flow meter diagnosis can be performed, but nitrogen oxide emissions and carbon dioxide emissions increase
Solution Approach 1:
The patent applies partial action by using only the necessary portion of recirculation cutoff (brief moments when diagnostic confidence is low) rather than complete or prolonged cutoff. The diagnostic system continuously monitors multiple air flow values and maintains recirculation whenever possible, cutting off only briefly when the median value falls outside the confidence interval, thus minimizing emission increases while ensuring diagnostic reliability.
Solution Approach 2:
The patent implements continuity of useful action by maintaining exhaust gas recirculation continuously whenever diagnostic confidence is high. The system only interrupts recirculation temporarily when diagnostic uncertainty arises, allowing the beneficial recirculation process to continue uninterrupted for the majority of the diagnostic period, thereby reducing overall emissions.
3Device complexity
If a single filling model is used for air flow estimation, then the diagnostic process is simple, but measurement precision deteriorates due to model inaccuracies
Solution Approach 1:
The patent applies segmentation by dividing the air flow estimation into multiple independent calculation paths: a filling model-based estimation and a turbocharger model-based estimation. Each model operates independently with its own assumptions and data requirements, allowing the system to segment the estimation task into manageable parts that can be individually optimized and validated.
Solution Approach 2:
The patent merges multiple air flow estimation results by calculating a median value from both the filling model estimation and the turbocharger model estimation. This combination approach integrates the strengths of different models while compensating for their individual weaknesses, improving overall measurement precision without requiring a single overly complex model.
4Quantity of substance
If turbocharger speed sensors or pressure sensors are used for air flow estimation, then air flow can be calculated, but reliability deteriorates due to sensor unavailability or unreliability
Solution Approach 1:
The patent uses available sensors as intermediaries to estimate air flow when direct measurement is unavailable. Instead of relying on a single sensor, the system uses multiple available sensors (turbocharger speed sensor if present, pressure sensors if present) as intermediate measurement points to calculate air flow through their respective models, maintaining reliability through multiple pathways.
Solution Approach 2:
The patent changes the input parameters based on sensor availability. When turbocharger speed sensors are unavailable, the system switches to using pressure sensor data or other available parameters. The diagnostic system dynamically adapts which parameters are used for estimation based on what sensors are actually present and functioning, ensuring reliable operation across different vehicle configurations.
Data Source
AI summary
This method for diagnosing the plausibility of drift of an air flow meter sensor adapted for the direct measurement of the fresh air flow entering a heat engine associated with an air intake circuit and a burnt gas exhaust circuit having exhaust gas recirculation to the intake controlled by a flow control valve or a throttle body, the method comprising no step of shutting off the exhaust gas recirculation valve, and comprising a step of calculating the median of the first, second, third and fourth fresh air flow values by different methods, and a step of comparing the value returned by the air flow meter with the previously calculated median.