NOx Adsorber Catalyst Condition Evaluation Using Lambda Accumulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current systems for evaluating the performance and degradation of NOx adsorber catalysts in diesel-powered engines are inadequate, as they rely on short-term air-fuel ratio measurements during regeneration events, which are not robust enough to account for the transient nature of modern engine operations and do not effectively assess the catalyst's ability to process excess hydrocarbons.
Innovation Solution
The proposed solution involves an apparatus and method that utilize the hydrocarbon processing capabilities of the NOx adsorber catalyst as a surrogate for its NOx reduction performance, using outlet air-fuel ratio values over extended periods during multiple regeneration events to determine the catalyst's condition, with modules to accumulate and analyze lambda values and set conditions based on predetermined thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If short-term air-fuel ratio measurements during regeneration events are used to evaluate NAC performance, then the evaluation system is simple to implement, but the measurement precision and reliability are insufficient due to the transient nature of engine operations
Solution Approach 1:
The system accumulates lambda values over multiple regeneration events before performing the evaluation. This preliminary accumulation of data from extended periods allows the system to capture the transient nature of engine operations, improving measurement precision while maintaining implementation simplicity through a straightforward accumulation and comparison process
Solution Approach 2:
The evaluation process continuously accumulates lambda values during each regeneration event and maintains this accumulation across multiple events. This continuous data collection ensures comprehensive coverage of engine operating conditions, enhancing evaluation reliability without adding system complexity
2Device complexity
If only air-fuel ratio values from the beginning of regeneration events are used, then the data processing is simplified, but the reliability of NAC condition assessment is reduced due to insufficient coverage of the entire regeneration process
Solution Approach 1:
The system continuously accumulates lambda values throughout the entire regeneration event from start to completion, rather than sampling only at the beginning. This continuous accumulation across the full regeneration cycle ensures all phases of the process are captured, improving reliability while keeping data processing straightforward through simple accumulation and threshold comparison
Solution Approach 2:
The system accumulates lambda values for the entire regeneration event duration, which may be more data than strictly necessary, but this excessive data collection ensures complete coverage of all regeneration phases. The simplicity of accumulating all values and comparing against a threshold maintains low processing complexity
3Device complexity
If the NAC condition is not accurately evaluated, then no additional diagnostic resources are required, but excess NOx emissions occur due to undetected catalyst degradation
Solution Approach 1:
The system continuously monitors lambda values during regeneration events and compares the accumulated values against predetermined thresholds to determine NAC condition. This feedback mechanism provides ongoing assessment of catalyst health, enabling timely detection of degradation and preventing excess NOx emissions without requiring complex diagnostic resources
Solution Approach 2:
The evaluation system uses existing lambda sensor data and regeneration event information already available in the exhaust aftertreatment system. By self-utilizing these existing resources for NAC condition assessment, the system achieves accurate monitoring to prevent NOx emissions without adding external diagnostic components
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 provides a more robust evaluation of the NOx adsorber catalyst's condition, enabling timely detection of degradation or malfunction, thereby ensuring compliance with emissions standards and reducing excess NOx emissions.
Implementation Method 1
the catalyst bed of the NAC is configured to intermittently trap or adsorb NOx and oxygen
Implementation Method 2
The release and reduction of NOx trapped on the NAC, otherwise called a regeneration of the NAC, occurs while the engine runs rich
Data Source
AI summary
According to one embodiment, an apparatus for evaluating the condition of a NOx adsorber catalyst (NAC) of an internal combustion engine system includes a rich condition timing module, NAC outlet lambda module, and NAC condition module. The rich condition timing module is configured to accumulate the total time during which exhaust gas exiting the NAC has a lambda value less than 1.0. The NAC outlet lambda module is configured to store NAC outlet lambda values of the exhaust gas while the exhaust gas exiting the NAC has a lambda value less than 1.0. The NAC condition module is configured to evaluate the condition of the NAC based on the total time during which exhaust gas exiting the NAC has a lambda value less than 1.0 and an accumulation of the stored NAC outlet lambda values.