Catalyst Degradation Diagnosis Using Oxygen Concentration Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for diagnosing catalyst degradation in internal combustion engines are inaccurate due to variations in oxygen concentration in exhaust gases, which affect the output of hydrocarbon sensors and complicate the assessment of catalyst performance.
Innovation Solution
A method that stabilizes the oxygen concentration of exhaust gases within a specific range (15% to 20% or ±2% variation) to accurately diagnose catalyst degradation by comparing diagnostic indicator values calculated from hydrocarbon sensor outputs with temperature-specific thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the oxygen concentration of exhaust gas is not controlled, then the diagnostic system can operate under various engine conditions, but the measurement precision of catalyst degradation is reduced due to oxygen concentration variations affecting sensor output
Solution Approach 1:
The patent applies parameter changes by establishing specific oxygen concentration ranges (15-20% or 10%±2%) as diagnostic conditions. The controller monitors oxygen concentration and only performs catalyst degradation diagnosis when the parameter falls within these predetermined ranges, thereby eliminating the adverse effect of oxygen variation on measurement precision while maintaining operational flexibility through conditional diagnosis.
2Measurement precision
If the oxygen concentration is stabilized within a specific range, then the measurement precision of catalyst degradation improves, but the complexity of the diagnostic system increases due to additional oxygen concentration monitoring and condition judgment
Solution Approach 1:
The patent utilizes the oxygen concentration specification component, which is already present in the exhaust gas analysis system for its primary function of analyzing exhaust composition. By adding the capability to use oxygen concentration data for diagnostic condition judgment, the system achieves multi-functionality without requiring entirely new hardware, thus improving measurement precision while minimizing the increase in system complexity.
3Measurement precision
If the diagnostic diagnosis is performed only under specific oxygen concentration conditions, then the measurement precision improves, but the productivity of the diagnostic system decreases due to restricted diagnostic opportunities
Solution Approach 1:
The patent implements periodic action by continuously monitoring oxygen concentration and performing catalyst degradation diagnosis periodically whenever the predetermined oxygen concentration conditions are satisfied. This approach ensures high measurement precision by restricting diagnosis to appropriate conditions while maintaining productivity through continuous monitoring and immediate diagnosis when conditions are met, rather than requiring scheduled interruptions.
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 approach ensures stable and high-accuracy diagnosis of catalyst degradation, reducing the impact of oxygen concentration variations and improving the reliability of catalyst performance assessment.
Implementation Method 1
a mixed potential hydrocarbon gas sensor (HC sensor) is used to detect the target gas
Implementation Method 2
a catalyst that is located along an exhaust path of an internal combustion engine, and oxidizes or adsorbs a target gas including at least one of a hydrocarbon gas and a carbon monoxide gas
Data Source
AI summary
A method of diagnosing a degree of degradation of a catalyst located along an exhaust path of an internal combustion engine, and oxidizing or adsorbing a target gas included in an exhaust gas and including at least one of HC and CO is disclosed. The method includes: a) determining whether an oxygen concentration of the exhaust gas is in a range of 15% to 20% or whether the oxygen concentration is 10% or more and varies in a range of ±2% or less of a predetermined value in a predetermined period of time; and b) diagnosing whether the catalyst is degraded when criteria in the step a) are satisfied. The step b) is performed by comparing a diagnostic indicator value calculated using an output value from a target gas detection component provided at a location downstream from the catalyst and a threshold corresponding to temperature of the catalyst.