Aftertreatment Catalyst Degradation Detection
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Solution Overview
Problem
Current aftertreatment systems in internal combustion engines face challenges in detecting catalyst degradation due to non-detectable symptoms and complexities arising from multiple catalysts with varying degradation modes and cross-reading of multiple constituents by sensors.
Innovation Solution
A method involving a controller with modules for interpreting test conditions, commanding catalyst efficiency tests, monitoring NOx conversion efficiency, and determining catalyst aging values, using sensors and reductant injection to assess NOx reduction catalyst degradation, including ammonia correction and feedforward aging adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple catalysts with differing degradation modes are used in the aftertreatment system, then the system can handle multiple emissions constituents, but detection of catalyst degradation becomes more complex
Solution Approach 1:
The patent segments the aftertreatment system into distinct functional zones with dedicated sensors. Upstream sensors detect specific constituents before they pass through particular catalysts, allowing independent monitoring of each catalyst's performance and degradation mode without cross-interference from multiple catalysts handling different emissions.
Solution Approach 2:
The patent introduces upstream composition sensors as intermediaries that measure emissions constituents before they interact with the catalysts. This allows the system to infer catalyst degradation by comparing upstream measurements with downstream sensor readings, decoupling the detection process from the complex interactions within the multi-catalyst system.
2Measurement precision
If composition sensors are used to detect catalyst degradation, then degradation can be monitored, but cross-reading of multiple constituents complicates accurate detection
Solution Approach 1:
The patent performs preliminary measurements of emissions constituents upstream of the catalysts before the constituents interact with the catalyst material. This allows the system to establish baseline concentrations and differentiate between actual catalyst degradation effects and natural variations in emissions composition, improving measurement accuracy.
Solution Approach 2:
The patent places sensors at specific locations with distinct measurement purposes - upstream sensors for baseline composition and downstream sensors for post-catalyst analysis. Each sensor zone is optimized for detecting specific degradation modes of particular catalysts, allowing precise local measurement without cross-reading interference.
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 accurate detection of catalyst degradation, improving the ability to maintain efficient emissions conversion and storage capacity by decoupling reductant storage effects and providing precise catalyst aging values.
Implementation Method 1
an aftertreatment system in the exhaust of internal combustion engines to meet emissions regulations or to reduce emissions of undesirable exhaust gas constituents. A variety of aftertreatment systems include one or more catalytic components
Implementation Method 2
Efficiency reductions can affect the conversion capability of the catalyst, and can also affect the storage capacity of the catalyst as an adsorption device
Data Source
AI summary
An exemplary embodiment is a system, including an internal combustion engine fluidly coupled to an exhaust gas flowpath, an aftertreatment system disposed in the exhaust gas flowpath, where the aftertreatment system includes a NOx reduction catalyst. The exemplary system includes a processing subsystem having a controller, where the controller includes modules structured to functionally execute operations for determining a catalyst degradation. The modules include a test conditions module, a testing module, a monitoring module, and a catalyst aging module. The test conditions module interprets a test conditions event occurrence for the NOx reduction catalyst, the testing module commands a catalyst efficiency test in response to the test conditions event occurrence, the monitoring module interprets operating condition(s) indicative of a NOx conversion efficiency during the catalyst efficiency test, and the catalyst aging module determines a catalyst aging value in response to the at least one operating condition.