Exhaust Gas Sensor Delay Estimation Using Fuel Injection Ramping
Solution Overview
Problem
Existing methods for monitoring exhaust gas sensor degradation in vehicles are complex and yield inconsistent delay estimates, leading to inaccurate indications of sensor performance, which can result in engine control degradation, increased emissions, and reduced drivability.
Innovation Solution
A method that estimates exhaust gas sensor degradation by using a time delay estimate based on a delay timer value, a nominal time delay, and an injection ramping time, improving the accuracy of oxygen sensor delay time estimation and simplifying the calibration process for engine control systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If previous complex approaches are used to monitor exhaust gas sensor degradation, then more comprehensive monitoring is achieved, but the delay estimates become less consistent and the system complexity increases
Solution Approach 1:
The patent extracts the fuel injection ramping time as a separate compensable parameter from the overall delay measurement. By isolating this specific time component (the time required to stop fuel injection across all cylinders), the system can compensate for it independently, leading to more consistent delay estimates without requiring complex comprehensive monitoring of all possible delay sources.
Solution Approach 2:
The patent changes the parameter being measured from raw delay time to compensated delay time by subtracting the injection ramping time component. This parameter transformation allows the system to achieve more consistent and accurate delay estimates by removing a known variable component from the measurement, simplifying the overall monitoring approach while improving precision.
2Measurement precision
If fuel injection ramping time is not compensated for in delay estimates, then the calculation is simpler, but the oxygen sensor delay time estimate becomes less accurate
Solution Approach 1:
The patent performs preliminary measurement of the fuel injection ramping time before calculating the oxygen sensor delay. By pre-determining this compensation value (the time to stop fuel injection across all cylinders), the system can then simply subtract it from the total delay measurement, achieving accurate delay estimation through a straightforward two-step process rather than complex real-time analysis.
3Productivity
If traditional delay estimation methods are used, then the calibration process is straightforward, but the calibration time required is excessive
Solution Approach 1:
The patent enables the system to automatically determine the fuel injection ramping time compensation value through self-testing procedures. The ECU performs automated fuel cut events and measures the actual injection ramping time without external intervention, allowing the system to self-calibrate the compensation parameter. This eliminates time-consuming manual calibration while maintaining accuracy.
Data Source
AI summary
A method and system for monitoring an exhaust gas sensor coupled in an engine exhaust is provided. In one example, the method adjusts an estimate of an exhaust gas oxygen sensor delay time based on a fuel injection ramping time. The fuel injection ramping time compensates for fuel that is injected to the engine while the engine enters or exits a fuel cut-off mode.