Catalyst Oxygen Storage Calculation with Sensor Delay Correction
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Solution Overview
Problem
Conventional exhaust purifying devices for internal combustion engines face challenges in accurately calculating the maximum oxygen storage amount of catalysts due to response delays in oxygen sensor outputs, leading to reduced calculation accuracy and limited opportunities for catalyst degradation assessment, especially at low temperatures.
Innovation Solution
An exhaust purifying device with a catalyst and oxygen sensor that includes a calculating section, temperature estimating section, learning section, correcting section, anomaly detecting section, and discarding section, which learns and corrects the maximum oxygen storage amount based on catalyst temperature and degradation, and discards learned functions when an abnormal response delay is detected to maintain calculation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If active air-fuel ratio control is performed to calculate maximum oxygen storage amount, then catalyst degradation can be recognized, but calculation accuracy is reduced when oxygen sensor response is delayed
Solution Approach 1:
The system performs preliminary actions by detecting oxygen sensor response characteristics in advance and comparing them against predetermined thresholds before final calculation. This allows the system to proactively identify delayed responses and prevent inaccurate calculations from occurring in the first place, rather than correcting errors after they happen.
Solution Approach 2:
The system implements feedback by continuously monitoring oxygen sensor output responses and using this information to adjust calculation processes. When the sensor response falls outside predetermined ranges, the system modifies its calculation approach or discards problematic data, ensuring that only reliable measurements contribute to the final maximum oxygen storage amount determination.
2Measurement precision
If temperature correction is applied to calculate corrected maximum oxygen storage amount, then temperature-related variations are compensated, but calculation accuracy is reduced when sensor response delay occurs
Solution Approach 1:
The system performs preliminary validation of oxygen sensor response characteristics before applying temperature correction calculations. By checking whether sensor responses fall within predetermined ranges in advance, the system ensures that temperature correction is only applied to reliable data, preventing propagation of errors from delayed sensor responses.
Solution Approach 2:
The system uses feedback from oxygen sensor response monitoring to dynamically adjust the temperature correction process. When sensor responses are within acceptable ranges, full temperature correction is applied; when responses are delayed or abnormal, the system modifies or discards the correction, ensuring calculation reliability is maintained alongside precision.
3Productivity
If learned functions are used for temperature correction, then calculation efficiency is improved, but accuracy is reduced when sensor abnormality is not detected
Solution Approach 1:
The system performs preliminary checks on oxygen sensor response characteristics before applying learned functions for temperature correction. By validating sensor responses in advance against predetermined ranges, the system ensures that efficient learned function calculations are only used when sensor data is reliable, preventing accuracy degradation from undetected sensor abnormalities.
Solution Approach 2:
The system implements feedback mechanisms that monitor oxygen sensor responses and use this information to control the application of learned functions. When sensor responses are normal, learned functions are applied for efficient calculation; when responses indicate abnormalities, the system adjusts or discards learned function applications, maintaining both efficiency and accuracy through adaptive control.
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 configuration prevents a reduction in the accuracy of the corrected maximum oxygen storage amount calculation caused by oxygen sensor response delays, allowing for more reliable catalyst degradation assessment without requiring individual temperature determination values.
Implementation Method 1
a commonly known oxygen sensor has a property to output approximately 0 V when the air-fuel ratio of an exhaust is leaner than the stoichiometric air-fuel ratio and to output approximately 1 V when the air-fuel ratio of the exhaust is richer than the stoichiometric air-fuel ratio
Implementation Method 2
a catalyst capable of storing oxygen and is located in the exhaust passage of an internal combustion engine
Data Source
AI summary
An electronic control device calculates the maximum actual oxygen storage capacity of a catalyst. The gradient of a linear expression formed between the catalyst temperature and the maximum oxygen storage capacity of the catalyst is stored for each degradation level of the catalyst. The gradient can be learned in accordance with the same temperature of the catalyst and the maximum actual oxygen storage capacity. When the maximum actual oxygen storage capacity is calculated, it is revised in accordance with the temperature of the catalyst, a reference temperature, the linear expression, and the learned gradient. The revised maximum oxygen storage capacity which is the maximum oxygen storage capacity when the temperature of the catalyst during the same calculation period is equal to the reference temperature is then calculated. If a response delay is detected in the output of an oxygen sensor, the gradient of the learned linear expression is discarded.