Intake Oxygen Sensor Zero Point Learning for EGR Control
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Solution Overview
Problem
Existing oxygen sensors in engine systems face challenges in accurately measuring EGR due to sensitivity to pressure changes and potential EGR valve leakage, leading to degraded EGR control.
Innovation Solution
A method is introduced to learn a reference point for the intake oxygen sensor during non-fueling conditions, adjusting EGR flow based on the sensor's output relative to a learned reference point and intake pressure, and diagnosing EGR valve leakage by comparing idle and deceleration fuel shut-off adaptations, allowing for compensation of pressure effects and leakage impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the intake oxygen sensor is used to measure EGR by detecting oxygen concentration changes, then EGR control capability is improved, but measurement precision deteriorates due to pressure sensitivity and EGR valve leakage
Solution Approach 1:
The patent introduces a correction factor as an intermediary element that mediates between the raw oxygen sensor signal and the final EGR calculation. This correction factor compensates for pressure effects and leakage impacts, allowing the oxygen sensor to maintain its adaptability for EGR control while restoring measurement precision through mathematical correction rather than physical modification
Solution Approach 2:
The patent changes the parameter space by introducing pressure correction factors and leakage compensation parameters. Instead of relying on raw oxygen concentration readings alone, the system transforms the measurement by applying correction coefficients that account for pressure variations and potential leakage, thereby maintaining EGR control versatility while improving measurement accuracy
2Adaptability or versatility
If the oxygen sensor is positioned downstream of the EGR valve to measure EGR dilution, then EGR measurement capability is improved, but reliability deteriorates due to EGR valve leakage corrupting sensor output
Solution Approach 1:
The patent performs preliminary diagnostics to detect EGR valve leakage before it corrupts the measurement. By monitoring the oxygen sensor output during specific engine conditions and comparing it against expected values, the system identifies leakage early and applies appropriate compensation or alternative calculation methods, maintaining both measurement capability and reliability
Solution Approach 2:
The patent implements a feedback mechanism where the oxygen sensor output is continuously monitored and compared against reference values. When leakage is detected through feedback analysis, the system adjusts its EGR calculation approach or applies correction factors, ensuring that the measurement capability is maintained while compensating for reliability issues caused by valve leakage
3Speed
If the oxygen sensor output is used directly for EGR feedback control, then control responsiveness is improved, but manufacturing precision deteriorates due to pressure-induced zero point deviations
Solution Approach 1:
The patent applies real-time parameter transformation by introducing pressure correction factors that adjust the oxygen sensor reading based on current intake pressure conditions. This allows the system to maintain fast responsive control by using the raw sensor signal while simultaneously compensating for zero point drift caused by pressure variations, effectively decoupling responsiveness from calibration accuracy
Solution Approach 2:
The patent performs preliminary calibration to establish baseline zero point characteristics under various pressure conditions. By pre-characterizing the sensor's pressure-dependent behavior during manufacturing or initial operation, the system can apply appropriate correction algorithms during normal operation, maintaining both rapid response and high precision without requiring complex real-time calibration
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 accuracy of EGR estimation and control by reducing the impact of pressure variations and EGR valve leakage, ensuring reliable EGR flow adjustments and enhanced engine performance.
Implementation Method 1
an intake oxygen sensor, such as an oxygen sensor, which may be employed to measure oxygen to determine the proportion of combusted gases in an intake passage of the engine
Implementation Method 2
Due to the sensitivity of the oxygen sensor to pressure, as well as aging, there may be large deviations in the 'zero point' at different engine operating conditions
Data Source
AI summary
Methods and systems are provided for accurately learning the zero point of an intake gas oxygen sensor during selected engine no-fueling conditions. The learned zero point is used to infer EGR flow and accordingly adjust EGR valve control. In addition, EGR valve leakage is diagnosed based on the zero point learned during a DFSO adaptation relative to a zero point learned during an idle adaptation.