Three-Way Catalyst Oxygen Storage Integration for Accurate Diagnosis
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Solution Overview
Problem
Existing internal combustion engine control systems inaccurately diagnose catalyst deterioration due to sensor signal delays and oxygen storage capacity changes, leading to suboptimal air-fuel ratio correction and reduced emission performance.
Innovation Solution
An internal combustion engine control device that integrates oxygen storage amount using sensors upstream and downstream of a three-way catalyst, determining integration start and stop positions based on air-fuel ratio changes to accurately calculate oxygen storage, thereby improving catalyst deterioration diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the oxygen storage amount is integrated from the air-fuel ratio change point to the oxygen concentration reversal point using a deteriorated oxygen sensor, then the integration period is extended, but the diagnosis accuracy deteriorates due to sensor signal delay
Solution Approach 1:
The system performs preliminary diagnosis of the oxygen sensor's deterioration state by analyzing the correlation between air-fuel ratio changes and oxygen concentration changes. Based on this preliminary assessment, it determines whether the oxygen sensor signal is reliable enough to be used for oxygen storage amount integration. This preliminary action prevents using delayed sensor signals that would compromise diagnosis accuracy.
Solution Approach 2:
The system dynamically adjusts the integration method based on the oxygen sensor's deterioration state. When the sensor is determined to be deteriorated, the system switches from using the oxygen concentration reversal point to using a predetermined time period for integration. This dynamic adaptation ensures accurate oxygen storage amount calculation regardless of sensor condition.
2Measurement precision
If the oxygen storage amount is integrated using a predetermined time period when the oxygen sensor is deteriorated, then the diagnosis accuracy is maintained, but the integration method becomes more complex
Solution Approach 1:
The system performs self-diagnosis of the oxygen sensor's deterioration state by analyzing the correlation between air-fuel ratio changes and oxygen concentration changes. Based on this self-assessment, it automatically selects the appropriate integration method (oxygen concentration reversal point or predetermined time period). This self-service approach maintains diagnosis accuracy without requiring external intervention or complex manual configuration.
3Measurement precision
If the oxygen concentration reversal point is used as the integration stop position, then the oxygen storage amount can be accurately obtained when the oxygen sensor is normal, but erroneous diagnosis occurs when the oxygen sensor is deteriorated
Solution Approach 1:
The system continuously monitors the correlation between air-fuel ratio changes and oxygen concentration changes to detect oxygen sensor deterioration. Based on this feedback, it determines whether to use the oxygen concentration reversal point or a predetermined time period for integration. This feedback mechanism prevents erroneous catalyst deterioration diagnosis by adapting the integration method to the actual sensor condition.
Data Source
AI summary
An internal combustion engine control device integrates an oxygen storage amount stored in a three-way catalyst in a period from an integration start position where combustion gas of an internal combustion engine obtained from an air-fuel ratio of exhaust gas starts to change from lean to rich or from rich to lean to an integration stop position where an oxygen concentration that has increased or decreased from before the integration start position is reversed.