Wide Range Air Fuel Sensor Rationality Diagnostic via Oxygen Storage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current exhaust gas recirculation (EGR) systems require intrusive diagnostic testing for air fuel sensors, which is inefficient and necessitates multiple sensors, and there is a need for a method to reduce the quantity of sensors and the intrusiveness of the testing process.
Innovation Solution
A method that estimates oxygen storage content in the catalytic converter, initiates a closed oxygen storage control event targeting a rich air-fuel equivalence ratio for specific engine cylinders, and uses a wide-range air-fuel sensor positioned upstream of the EGR cooler to determine if the sensor is operating within predefined criteria, allowing for reduced sensor usage and less intrusive testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple air fuel sensors are used in each output path from engine cylinders for EGR system control, then the reliability of sensor operation can be ensured, but the device complexity and quantity of sensors increase
Solution Approach 1:
The patent combines the diagnostic function into a centralized control system that manages multiple sensors through a unified diagnostic routine rather than requiring separate dedicated sensors for each cylinder. The engine control unit integrates sensor rationality testing and EGR control functions, reducing the total sensor quantity while maintaining reliability through shared diagnostic resources.
Solution Approach 2:
The diagnostic system is designed to universally test multiple air fuel sensors using a single diagnostic routine that can evaluate sensors in different output paths. The control system performs multi-functional operations including sensor rationality testing, oxygen storage estimation, and EGR control through a unified diagnostic framework that serves multiple sensing functions.
2Measurement precision
If intrusive diagnostic testing is performed on each air fuel sensor to confirm proper operation, then measurement precision can be ensured, but the ease of operation and system intrusiveness worsen
Solution Approach 1:
The system performs preliminary rationality testing of air fuel sensors during normal operation by comparing sensor outputs against expected values based on oxygen storage estimates. The diagnostic routine proactively validates sensor functionality before critical failures occur, using pre-calculated oxygen storage thresholds to assess sensor rationality without requiring intrusive external testing.
Solution Approach 2:
The diagnostic system uses the engine's own operational parameters and oxygen storage data to self-validate sensor functionality. The control unit leverages existing sensor inputs and oxygen storage estimates to perform automated rationality checks, eliminating the need for external diagnostic equipment or intrusive manual testing procedures.
3Reliability
If power is provided to each sensor for rationalization testing to ensure EGR system initiation, then the reliability of EGR operation is improved, but the use of energy increases
Solution Approach 1:
The diagnostic system continuously monitors sensor rationality using existing operational data and oxygen storage estimates during normal engine operation. Rather than performing periodic high-power activation tests, the system maintains continuous low-power validation by comparing sensor outputs against dynamically calculated thresholds, eliminating the need for high-power testing pulses while ensuring EGR system reliability.
Data Source
AI summary
A method for operating an exhaust gas recirculation system using rationality diagnostics for an automobile vehicle includes: estimating an oxygen storage content (OSC) of a catalytic converter of a vehicle; comparing an amount of oxygen stored in the catalytic converter to an OSC threshold; initiating a closed oxygen storage control (COSC) event for a predetermined one of multiple cylinders of an engine of a vehicle if the OSC threshold is met or exceeded, the COSC event targeting a rich air-fuel equivalence ratio (EQR) for the predetermined one of the multiple cylinders; and directing a fuel injector communicating with the predetermined one of the multiple cylinders to operate the predetermined one of the multiple cylinders at the rich EQR.