Oxygen Sensor Calibration via Exhaust Flow Dynamics
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Solution Overview
Problem
Conventional internal combustion engine controllers face challenges in accurately determining when the oxygen concentration around the oxygen concentration sensor has reached atmospheric levels, leading to erroneous or infrequent calibration during atmospheric learning, due to varying delay times influenced by engine speed, vehicle speed, and gear shift position.
Innovation Solution
The controller performs atmospheric learning when the changing rate of the oxygen concentration sensor's output value drops below a predetermined threshold and when the total volume of intake air exceeds a threshold since fuel cutoff, ensuring accurate calibration by determining the oxygen concentration has reached atmospheric levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wait time is set shorter than the delay time, then the atmospheric learning frequency is increased, but the calibration accuracy deteriorates due to erroneous learning before oxygen concentration reaches atmospheric levels
Solution Approach 1:
The control unit continuously monitors the output value of the oxygen concentration sensor and uses this feedback to determine when atmospheric learning should be performed. By detecting when the sensor output stabilizes at a level indicating atmospheric oxygen concentration, the system dynamically adjusts the learning timing based on real-time feedback rather than using a fixed wait time, thus preventing erroneous calibration while maintaining high learning frequency.
Solution Approach 2:
The patent transitions from a static fixed wait time approach to a dynamic determination method where the wait time varies based on engine operating conditions. The control unit adjusts the atmospheric learning timing dynamically by monitoring the changing rate of the sensor output value, allowing the system to adapt to different delay times caused by varying engine speeds, vehicle speeds, and gear positions, thereby resolving the contradiction between learning frequency and accuracy.
2Measurement precision
If the wait time is set longer than the delay time, then the calibration accuracy is improved, but the atmospheric learning frequency decreases
Solution Approach 1:
The system uses continuous monitoring of the oxygen concentration sensor output to provide feedback on when the delay time has elapsed. This feedback mechanism allows the control unit to initiate atmospheric learning immediately when the conditions are met, rather than waiting for a predetermined extended period, thus maintaining high learning frequency while ensuring accuracy.
Solution Approach 2:
The control unit prepares for atmospheric learning by continuously monitoring sensor output and identifying when the delay time condition is satisfied. Once the preliminary condition (sensor output stabilization indicating atmospheric concentration) is detected, the atmospheric learning is immediately executed, eliminating unnecessary waiting time and maximizing learning frequency without compromising accuracy.
3Device complexity
If the wait time is fixed based on engine speed, vehicle speed, and gear shift position, then the control complexity is reduced, but the calibration accuracy deteriorates due to exhaust gas recirculation effects
Solution Approach 1:
The patent introduces a feedback-based determination method that monitors the actual sensor output to detect when atmospheric conditions are reached. This feedback approach replaces or supplements the fixed wait time calculation, allowing the system to account for exhaust gas recirculation effects and other variable conditions without requiring complex predictive models, thus improving accuracy while maintaining reasonable control complexity.
Data Source
AI summary
The internal combustion engine controller includes an oxygen concentration sensor outputting an electric signal having a value depending on an oxygen concentration in an exhaust gas flowing through an exhaust passage of an internal combustion engine, and a control unit controlling fuel injection amount depending on at least the electric signal, the control unit being capable of performing atmospheric learning to calibrate the oxygen concentration sensor. The control unit is configured to perform the atmospheric learning when a changing rate of the value of the electric signal is lowered from above a predetermined threshold rate to below the predetermined threshold rate after a time of start of cutoff of fuel supply to the engine.