Catalyst Deterioration Diagnosis Using Adaptive Oxygen Storage Thresholds
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Solution Overview
Problem
Existing catalyst deterioration diagnostic devices are inadequate for diagnosing catalyst degradation in internal combustion engines, particularly in hybrid vehicles, as they fail to accurately assess oxygen storage capacity when Exhaust Gas Recirculation (EGR) is not implemented, leading to inconsistent diagnostic results due to variations in EGR status.
Innovation Solution
A diagnostic device and method that adjusts the criteria for diagnosing catalyst deterioration based on whether EGR is implemented or not, using different oxygen storage capacity thresholds and correction factors to account for variations in EGR status, ensuring accurate diagnosis regardless of EGR conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If catalyst deterioration diagnosis is performed using a single oxygen storage capacity threshold regardless of EGR status, then the diagnostic method is simple, but diagnostic accuracy deteriorates when EGR is not implemented
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the oxygen storage capacity threshold based on EGR status. When EGR is implemented, a first threshold is used, while when EGR is not implemented, a second (higher) threshold is used. This parameter adjustment resolves the contradiction by maintaining diagnostic accuracy across different operating conditions without requiring complex multi-mode diagnostic logic.
2Measurement precision
If different oxygen storage capacity thresholds are used based on EGR status, then diagnostic accuracy is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamics by making the diagnostic threshold flexible and adaptive rather than fixed. The threshold dynamically switches between two values based on real-time EGR status detection. This dynamic approach improves accuracy without significant complexity increase, as the switching logic is straightforward and integrated into the existing diagnostic flow.
3Reliability
If catalyst diagnosis is performed only when EGR is implemented, then diagnostic conditions are controlled, but diagnostic opportunity is reduced in cold climates and hybrid vehicles
Solution Approach 1:
The patent applies universality by making the diagnostic system applicable to both EGR-implemented and EGR-non-implemented conditions. By establishing a second, higher threshold specifically for non-EGR conditions, the system can reliably diagnose catalyst deterioration across all operating scenarios, including cold climates and hybrid vehicle operations where EGR may not be active. This multi-functional approach maintains reliability while significantly increasing diagnostic opportunity.
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
Enables effective diagnosis of catalyst deterioration regardless of EGR status, ensuring reliable assessment of catalyst health even when EGR is not implemented, thereby improving diagnostic accuracy and coverage.
Implementation Method 1
when the air/fuel ratio of exhaust gas flowing to the catalyst is leaner than the stoichiometric air/fuel ratio, excess oxygen contained in the exhaust gas is adsorbed and retained
Implementation Method 2
where the air/fuel ratio of exhaust gas flowing to the catalyst is richer than the stoichiometric air/fuel ratio, the adsorbed and retained oxygen is released
Data Source
AI summary
A device for diagnosing deterioration of a catalyst by a decrease in oxygen storage capacity, in which the oxygen storage capacity by which the catalyst deterioration is diagnosed to be present when exhaust gas recirculation is not implemented is higher than the oxygen storage capacity by which the catalyst deterioration is diagnosed to be present when the exhaust gas recirculation is implemented.